AN 3.63 Buddha walking WHILE in jhāna, has two close EBT parallels Bhikkhu Sujato missed

 

    AN ^8.63 - AN 8.63 Saṅkhitta: A Teaching in Brief
        AN ^8.63.1 – (4bv brahma vihāras done simultaneously with 4 jhānas)
        AN ^8.63.1.1 – (4bv #1: mettā me ceto-vimutti)
            AN ^8.63.1.1.2 – (combine 4bv with samādhi in 3 ways for four jhānas)
        AN ^8.63.1.2 – (4Bv #2: karuṇā me ceto-vimutti)
            AN ^8.63.1.2.2 – (combine 4bv with samādhi in 3 ways for four jhānas)
        AN ^8.63.1.3 – (4Bv #3: muditā me ceto-vimutti)
            AN ^8.63.1.3.2 – (combine 4bv with samādhi in 3 ways for four jhānas)
        AN ^8.63.1.4 – (4Bv #4: upekkhā me ceto-vimutti)
            AN ^8.63.1.4.2 – (combine 4bv with samādhi in 3 ways for four jhānas)
        AN ^8.63.2 – (4sp sati-'paṭṭhāna done simultaneously with 4 jhānas)
        AN ^8.63.2.1 – (4sp #1: seeing body as it actually is)
            AN ^8.63.2.1.2 – (combine 4sp with samādhi in 3 ways for four jhānas)
        AN ^8.63.2.2 – (4sp #2: seeing sensations as they actually are)
            AN ^8.63.2.2.2 – (combine 4sp with samādhi in 3 ways for four jhānas)
        AN ^8.63.2.3 – (4sp #3: seeing the mind as it actually is)
            AN ^8.63.2.3.2 – (combine 4sp with samādhi in 3 ways for four jhānas)
        AN ^8.63.2.4 – (4sp #4: seeing Dharma as it actually is)
            AN ^8.63.2.4.2 – (combine 4sp with samādhi in 3 ways for four jhānas)
        AN ^8.63.3 – (all of these jhānas and samādhis and sati are done simultaneously in all four postures: is blissful and comfortable)
        AN ^8.63.4 – (conclusion: monk practicing in this way becomes an arahant)

MA 76 郁伽支羅經 at Ukkācelā ∥AN ^8.63

(derived from BDK trans. 2020)
    MA ⁷⁶ - MA 76 郁伽支羅經 at Ukkācelā
        MA ^76.1 - (4sp #1: Kāya anu-passana internally, externally, both)
            MA ^76.1.2 - (do 4sp with 3 way samādhi jhāna quality in all postures)
        MA ^76.2 - (4sp #2: Vedana anu-passana internally, externally, both)
            MA ^76.2.2 - (do 4sp with 3 way samādhi jhāna quality in all postures)
        MA ^76.3 - (4sp #3: Citta anu-passana internally, externally, both)
            MA ^76.3.2 - (do 4sp with 3 way samādhi jhāna quality in all postures)
        MA ^76.4 - (4sp #4: Dhamma anu-passana internally, externally, both)
            MA ^76.4.2 - (do 4sp with 3 way samādhi jhāna quality in all postures)
        MA ^76.8 - (STED 4bv: metta, karuna, mudita, upekkha)
            MA ^76.8.2 - (do 4bv while walking and wandering)
        MA ^76.12 - (fruits of the practice)
        MA ^76.13 - (conclusion: khīnā jāti! Destroyed is birth!)

MA 76 is constructed slightly differently than AN 8.63, especially in brahma vihara section,

but the themes of walking while doing sati, jhāna, and brahma vihāra are there.

And MA 76 is even more explicit and unequivocal about 4 jhānas being done simultaneously with satipaṭṭhāna in all 4 postures than AN 8.63.

76.1 - (4sp #1: Kāya anu-passana internally, externally, both)

世尊告曰：「比丘！當如是學，令心得住，在 內不動無量善修，復觀內身如身，行極精 勤，立正念、正智，善自御心，令離慳貪，意無 憂慼。	The World-honored One said: Monk, you should train in such a way that the mind becomes settled, remaining imperturbable within, developing immeasurable wholesome factors. Again, [anu-passana] continuously-see the body as a body internally, dwelling with utmost diligence, with right mindfulness and right [sampajāno] lucid-discerning established, taming your own mind well, so that covetousness is left behind and the mind is without dejection.
復觀外身如身，行極精勤，立正念、正 智，善自御心，令離慳貪，意無憂慼。	Again, [anu-passana] continuously-see the body as a body externally, dwelling with utmost diligence, with right mindfulness and right [sampajāno] lucid-discerning established, taming your own mind well so that covetousness is left behind and the mind is without dejection.
復觀內 外身如身，行極精勤，立正念、正智，善自御 心，令離慳貪，意無憂慼。	Again, [anu-passana] continuously-see the body as a body internally and externally, dwelling with utmost diligence, with right mindfulness and right [sampajāno] lucid-discerning established, taming your own mind well so that covetousness is left behind and the mind is without dejection.

76.1.2 - (do 4sp with 3 way samādhi jhāna quality in all postures)

比丘！如此之定， 去時、來時當善修習，住時、坐時、臥時、眠時、寤 時、眠寤時亦當修習。

Monk, such [samādhi] undistractible-lucidity should be well developed when going and coming. You should develop it when standing, when sitting, when lying down, when going to sleep, when waking up, and when both sleeping and waking up.

復次，亦當修習有覺 有觀定、無覺少觀定，修習無覺無觀定，亦當 修習喜共俱定、樂共俱定、定共俱定，修習 捨共俱定。

Again, you should develop [samādhi] undistractible-lucidity with [vitakka] directed-thought and [vicāra] evaluation, . . . [samādhi] undistractible-lucidity without [vitakka] directed-thought but with only [vicāra] evaluation; . . . you should well develop [samādhi] undistractible-lucidity without [vitakka] directed-thought and without [vicāra] evaluation; and you should well develop [samādhi] undistractible-lucidity conjoined with rapture, . . . [samādhi] undistractible-lucidity conjoined with happiness, . . . [samādhi] undistractible-lucidity conjoined with being concentrated, and you should well develop [samādhi] undistractible-lucidity conjoined with [upekkha] equanimous-observation.

Conclusion

In AN 3.63, Bhikkhu Sujato admits the Buddha is indeed walking WHILE in the four jhānas: “one in such a state” while walking.

He then goes on to dismiss AN 3.63 as a curiosity, exception to the rule of jhāna being a disembodied state with no thought, with no Agama Chinese parallel.

But if you read AN 8.63 (above), you'll see that AN 3.63 is exactly the Buddha doing what his general instructions to all monks in AN 8.63 is talking about.

So AN 3.63 is not just about the Buddha being happy, it's about the Buddha eating his own cooking, following his own instructions on walking and doing jhāna, satipaṭṭhāna, all at the same time. 

Just as he tells ALL the monks to do, not just an exceptional thing only the Buddha should attempt.