[takluyver]

I'm guessing Windows gets a pass because you can still fairly easily bypass the signature check - it's effectively a warning rather than a hard block. It sounds like for (mainstream) Android, the only workaround will be to plug it into a PC and use adb there to install an unsigned app, which is considerably harder. Installing a custom ROM will presumably get around it too, but that's tough, and various government and banking apps etc tend to refuse to run because of attestation.

Apple is of course locked down, but that's not news. The anger is because Android was the better option on this dimension.

[lukevp]

Is rooting the same as a custom rom nowadays? And enabling developer options won’t allow installation of unsigned apps either?

[takluyver]

They could add a developer option to bypass the new restriction, but as far as I know they haven't said they'll do that, and I don't see any reason why they would. The adb bypass is probably good enough for actual developers.

Apps can certainly detect if a phone is rooted and refuse to work, like with a custom ROM. It's up to the developer what they care about, but this is not unusual. There are ways to try to trick the check into passing, but it sounds like the kind of thing that might break on any update.