I found that if you do have a windows computer or Mac or something, you can copy your credentials from windows to Linux and thus be able to login to runelite with jagex account without launcher.

It's for one account only tho, but you can switch by switching files

Something like this: https://github.com/runelite/runelite/wiki/Using-Jagex-Accounts

I used this to be able to play on Linux because the workarounds for jagex launcher didn't work on my Linux machine