@rayslava very hacky approach, probably, some plain text accounting, for phones there are simple apps to add spending transactions and at home import both into main sheet

they have some iOS client here https://hledger.org/mobile.html, but also hledger is most advance at this moment, and if you are about self-host it, hledger has web mode, for adding transactions

not sure about join accounts, but I heard that some quite big businesses instead of all these accounting proprietary software are using PTA