I’m surprised you didn’t look at GNUCash, I used it back in the day when starting out my business. It always seemed to be more focused on record keeping than invoicing. It has double entry accounting and support for maintaining information on shares, bonds and investments, and I think it had OFX and HBCI support. You could store the data file on Dropbox or Syncthing or perhaps Onedrive to allow access on all your PC’s and it would still be available offline
This article seems to mention a way to link your bank account for live updates of transactions: https://wiki.gnucash.org/wiki/AqBanking