गोविन्द भाष्य (श्रील बलदेव विद्याभूषण - अचिन्त्यभेदाभेद वेदान्त ब्रह्मसूत्र भाष्य सटीक)

The prāṇa here must refer to the Supreme Personality of Godhead, who is
present in everyone's heart as the Supersoul. Prāṇa here cannot refer to the
individual spirit soul. Why? Śrīla Vyāsadeva explains: tathānugamāt (because of
the context). The prāṇa described here is intelligence, the self, and transcendental
bliss. He is free from old-age and death. These attributes clearly indicate that the
word prāṇa here refers to the Supreme Personality of Godhead.
At this point someone may raise the following objection: Is it not true that to
interpret the word prāṇa here is mean Brahman is very inappropriate? Mahārāja
Indra is speaking, and he says prāṇo 'smi (I am prāṇa). The speaker is Mahārāja
Indra, and he clearly refers to himself. He then proceeds to further identify
himself, saying: tri-śīrṣāṇaṁ tvaṣṭram ahanam aruṇmukhān ṛṣīn śalāvṛkebhyaḥ
prayacchan (I killed Vṛtrāsura, the three-headed son of Tvaṣṭā, and I gave the
Aruṇmukha sages to the śalāvṛkas). All this shows that the Indra described here is
an individual spirit soul who advises the living entities to worship him. Even
though at the end of this passage prāṇa is described as ānanda (transcendental
bliss), this also is not inconsistent, because the transcendental glories of the
individual spirit souls are also described in the Vedic literatures. In fact, when
Indra says he is prāṇa and everyone should worship him, he refers to himself, the
individual spirit soul Indra. Indra's statement may be compared to the advice of
the Vedic literature: vācaṁ dhenum upāsīta (One should worship the goddess of
speech just as one worships the cow). Because Mahārāja Indra is the strongest of
living entities, and because strength is identified with the living-force (prāṇa), he
identifies himself with that prāṇa. This is perfectly in accord with the statement of
Vedic literature: prāṇo vai balam (the living-force is strength). In this way it should
be understood that the words prāṇa and indra here refer to a specific individual
spirit soul.
Śrīla Vyāsadeva refutes this argument in the next sūtra.
Sūtra 29
na vaktur ātmopadeśād iti ced adhyātma-sambandha-bhūma hy asmin
na—not; vaktuḥ—of the speaker; ātma—of the self; upadeśāt—because of the
instruction; iti—thus; cet—if; adhyātma—to the Supreme Personality of Godhead;
sambandha' references; bhūma—abundance; hi—indeed; asmin—in this Upaniṣad.
If it is said that the speaker here refers to himself, I say that is not true. In this
passage there are many references to the Supreme Personality of Godhead.
Purport by Śrīla Baladeva Vidyābhūṣaṇa