Yeah, probably best to keep your phone. With regard to your future Fairphone: I completely understand your point — I’m not a fan of tinkering either. However, based on what I’ve seen in this forum, stock Android seems to cause more issues than /e/OS, especially after the Android 15 update. All the banking apps I use from Sparkasse (Germany) work flawlessly on my Fairphone 6 — including S‑PushTAN, Mobiles Bezahlen, and S‑ID‑Check. That may vary, of course, so it could be helpful to ask other users about their experiences with your specific bank.
I’m really not trying to convert anyone, but my general impression from the Fairphone and /e/OS forums is that user experiences with /e/OS tend to be more positive than with Android. Still, my own extremely positive experience with /e/OS (after only one week) might not be typical.