How? Having an unlocked bootloader or root breaks Safety Net, which disables many apps. You need an unlocked bootloader to install custom ROMs.

Magisck used to be a workaround, but Google has been sabotaging it at the OS and hardware layers, so it wasn’t working the last time I tried a few years ago.

Once updates end in October, Windows 10 won’t be secure and probably shouldn’t be allowed to connect to the internet. It will still continue to function though. You can buy a year of extended support for Windows 10 for $30, but it’s unclear whether there will be support after that.

Probably best to start switching to something else, or plan to run that PC offline.