My personal finances are obnoxiously complex, and I track everything using a tool called hledger. If you have some programming knowledge, it's super easy to write your own tools to work with the ledger files to generate really specific reports, streamline transaction entry, stuff like that. You can basically work it to conform to any financial workflow you can imagine.

There are plenty of other privacy friendly tools available as well. You've mentioned GNUCash already so I'll skip that:

• There is a whole ecosystem of tools centered around the "plaint text accounting" umbrella that hledger falls into. This site has a lot of good info: https://plaintextaccounting.org/

• Firefly-iii: i used this for several years. It's quite opinionated with how it handles your finances, which can be good or bed depending on if it meshes with the way you work. It's also web based and requires you to host it somewhere which can be a high barrier to entry for many. It's also a bit tedious to manually enter transactions (IMO).

• Silverstrike: Another hosted web based app similar to Firefly-iii. I haven't used this one personally but people say good things about it.

• Spreadsheets: Literally just whatever spreadsheet software you like. Spreadsheets are powerful, and if all you really care about is keeping track of account balances and not detailed transaction info, it may be the easiest option.

Any of these options can theoretically support automatic transaction importing as well, although setup can be tricky at best, and most integrations will require you to hand over your info to a 3rd party like Plaid because banks suck and don't have APIs (and often deliberately obfuscate their website code to make scraping difficult).