You already need to submit to iOS or stock Android for a myriad of banking or government apps that use remote attestation to verify that you are running "untampered" software.
FWIW this has not been my experience in the US, I've always been able to use websites for these things. I use my phone for almost nothing important since I don't trust it. But yes, I fear we are heading in that direction too.
I keep seeing this where? What banks don’t allow you to go to their website and use them from your phone? Which government apps don’t also have websites?
Not in the western countries yet, I guess. I live in Thailand and have accounts in two banks and both of them only allow usage through an app that's only available through the App/Play store. Android version of Krungthai's bank app freaks out if you have developer settings enabled (even without changing anything, just enabling the access is enough to lock you out). And to use that app in the first place, you have to go to a branch and have staff set the app for, as passing the facial scan checks is impossible for foreigners.
Several German banks (at least mine, one of the bigger ones) exclusively have you use an app for 2FA, you can still log via the website if you are lucky (as long as you have that one saved) but not do any transactions. So I would call that required.
In the EU there is Strong customer authentication [0], part of the PSD2 (Revised Directive on Payment Services).
I read as much about it from the official sources as I could about a year ago, so I might be wrong here. From what I remember even though no specific mention of Android or iOS attestation was made, a "strong" form of 2FA is needed. Stronger than TOTP.
In my country most banks I talked with require a mobile app for 2FA even if you're logging in from a desktop browser. I haven't (and will not) install a banking app on my phone, so I'm not sure if it would work if the phone doesn't pass the attestation (e.g., Play Integrity on Android). I wanted to install the app in an AOSP VM, but no bank would even send me the apk file - they all want me to download it from Google for some reason.
Another option was to pay for a hardware device from a third-party company.
I was lucky that one bank still uses SMS 2FA. It's weaker than TOTP (depending on your threat model, I guess), but I prefer it.
My other option is either to:
* have a smartphone;
* have an "approved" OS from an American company;
* have an account with said American company so I can download the app from the company's repository;
* run closed source software on my smartphone.
or to
* pay for a USB device from a third-party company;
* that barely works with Linux;
* that requires a closed source program to run;
* that doesn't work with VMs and troubleshooting was a pain (I tried).
What I want is to use TOTP. I would actually store the secret on another device, as I'm not opposed to the idea of 2FA in general. And I would be fine if my money were drained as a result of me being hacked. If I had millions in my account, I could just use a separate computer only for the banking, but still a computer I chose.
Online banking (a superset of "mobile" banking) is very important for a person to have in order to participate in society. The ability to choose what hardware and software to use is also very important. The ability to not associate oneself with third-party companies, to accept their ToS and to pay them money is also very important. Therefore, I think those things should be my rights. I'm not complaining about a gym or a pizza place requiring a mobile app here, after all.
Remote attestation is evil.