Have you tried packaging zulujdk 17 and thinkorswim and installing them with rpm-ostree?

Personally I use ledger for something like this. It’s a double-entry accounting system and from what I’ve heard similar to GnuCash though I haven’t used that one.

Parsing and Categorizing of bank statements would probably need to be done manually or with a self-developed script, though maybe there’s already something made for that. I haven’t looked so far.

That’s optimistic