The only downside to this is that banking apps won't work anymore. Some of them won't work without GMS, or with a custom ROM, or if Knox is triggered (Smasnug), or even if the bootloader is unlocked.
Unfortunately, more and more banks are deprecating their web apps in favor of mobile apps, 'cause who doesn't have a smartphone?.
Basically every banking app in my country works fine with custom rom. It even works without safetynet and with root. Hell I fucking had more issues with the MCDONALDS app that blocked me
Oh man, I wish that we could have that here. One app from one of the bigger banks here, straight up refuses to run if you didn't download it from the Play Store (like Aurora).
I am lucky enough to be able to avoid the GSM only banks and choose banks that do work on degoogled phones. Honestly, thanks to the ongoing trade-war between China and the US, degoogled phones will become more common and force banks to cater to those people. I'm not worried.