Hello,

I've been a happy Belgian LineageOS + OnePlus power user for years now :)

However,
I only run with MicroG (LineageOSforMicroG to be exact) + Magisk (root),
which makes things a bit harder.

Itsme is a pain in the ass when it comes down to root,
they really don't allow it.
You'll find yourself in a never ending battle,
of you working around root detection methods, and them patching them.
If you're up for it, you can join that battle on the XDA Developers forum though :)

However, luckily you don't really need Itsme!
You can log in on CSAM,
and there enable username + password + 2FA authentication.
Since I've done that, I haven't needed Itsme anymore!

~~Belfius is rather chill then it comes down to root.~~
~~They just show a pop-up about it,~~
~~which you can dismiss, and call it a day.~~
See comment for Belfius: https://discuss.tchncs.de/post/5887554/11413267

Can't vouch for other banking apps,
however if they complain,
the XDA Developers forum is your friend

Payconiq doesn't work on MicroG though,
due to the GApps QrCode library not being implemented in MicroG yet.
This also affects my ability to scan QrCodes in Belfius,
so I just save contacts, and do direct payments without QrCodes instead.

GApps is a piece of spy-ware in my opinion.
However if you're willing to install that instead of MicroG on your LineageOS,
then you should not run into such QrCode scanning issues.

MicroG is a light weight open source implementation of GApps,
which does respect your privacy!

Magisk is an awesome piece of open source software,
allowing you to gain root access,
and modify the working of your Android through modules,
without doing permanent changes to the /system partition.

However if you're able/willing to live without this,
you should run into even less issues / complaining apps.

Or you could choose to dive onto XDA Developers forum again,
to learn on how to hide your root + pass SafetyNet.

TLDR
If you install GApps, and do not root,
you should pass SafetyNet, no apps should complain,
and everything should work.

Whether the apps you need work depends less on the device than on the OS and whether the app works without Google services or at least with MicroG. I have no experience with this, but there are a few community-lists:

Here you can find a list of whether and which banking apps run with eOS (i.e. with MicroG): https://community.e.foundation/t/list-banking-apps-on-e-os/33091

Here a list of apps in general: https://community.e.foundation/t/list-apps-that-work-or-do-not-work-with-microg/21151 Doccle is listed there: "‘Doccle’ (Belgian administration app) Works perfect without Google."

Oneplus 7 Pro here. the ING app works fine but itsme was a bit tricky to set up since I had to revert to an old version, log in and then update for it to work. Payconiq is integrated into the ING app so I don't now how well it's working on its own.

That's funny, I have a OnePlus6 too. Still have to switch it to LineageOS, so unfortunately I can't help you.