Namaskaram Swami,
Velukkudi Swami has mentioned multiple times that we Sri Vaishnavas respect every devatha but with the understanding that Perumal is the antaryami in all of them and our surrender is only to Perumal. “Our acharyas have said we should not compare bhagavan with others.” = this is correct but by saying I’m Shiva among Rudras, Lord is not equating Himself to them. Krishna is only telling us that I’m the best of the best.
In BG 10.2 He starts with
na me viduḥ sura-gaṇāḥ
prabhavaṁ na maharṣayaḥ
aham ādir hi devānāṁ
maharṣīṇāṁ ca sarvaśaḥ
The key is aham ādir hi, which confirms that He is not giving that part to anyone else. And He also reconfirms in 10.8 that everything emanates from Him
ahaṁ sarvasya prabhavo
mattaḥ sarvaṁ pravartate
iti matvā bhajante māṁ
budhā bhāva-samanvitāḥ
The above mention about Shiva, which is BG 10.23 is a response to a question asked by Arjuna in BG 10.27 on how to constantly remember Krishna through His various forms. This question by Arjuna was raised to help souls, based on their different levels of conditioning, to remember (paricintayan) the Lord and finally go to Him.
kathaṁ vidyām ahaṁ yogiṁs
tvāṁ sadā paricintayan
keṣu keṣu ca bhāveṣu
cintyo ’si bhagavan mayā
Krishna also concludes the chapter in BG 10.42 saying that what is the use of all this knowledge (kiṁ jñātena)
atha vā bahunaitena
kiṁ jñātena tavārjuna
viṣṭabhyāham idaṁ kṛtsnam
ekāṁśena sthito jagat
The scene continues to the next Chapter (11) where Arjuna desires and sees the Universal form of the Lord and finally in BG 11.50, Sanjaya tells Dhṛtarāṣṭra that based on the request from Arjuna, the Lord showed his original form (svakaṁ rūpaṁ), which is the Narayana or the four-armed form.
sañjaya uvāca
ity arjunaṁ vāsudevas tathoktvā
svakaṁ rūpaṁ darśayām āsa bhūyaḥ
āśvāsayām āsa ca bhītam enaṁ
bhūtvā punaḥ saumya-vapur mahātmā
So simply our acharyas focussed on the Narayana form and Azhwars mostly focussed on the Krishna form as Krishna himself said in BG 11.52 after showing His human-like form on the request from Arjuna
śrī-bhagavān uvāca
su-durdarśam idaṁ rūpaṁ
dṛṣṭavān asi yan mama
devā apy asya rūpasya
nityaṁ darśana-kāṅkṣiṇaḥ
Hope this helps.
adiyen.