The reason microG didn't help is that it's solving a different problem. It reimplements the Play Services APIs, so push notifications and maps come back, but it can't produce a Play Integrity verdict — that needs an attestation signed by Google and tied to a locked bootloader and the device's hardware keystore. Banks almost always check MEETS_DEVICE_INTEGRITY, and nothing running in userspace can fake it.

So "a bank whose app works without Play Services" really means "a bank that doesn't call Play Integrity". Annoyingly that's the question to ask them and nobody in support will know what you're talking about.

On the 2027 verification thing driving this: from what's been written about it, it applies to certified devices, which means ones shipping GMS, and non-certified ROMs sit outside it. If that holds then degoogling removes that worry rather than racing it. I haven't seen Google state it in their own words though, so I wouldn't plan around it yet.