Not sure if that fits your bill, but we have successfully used
- https://ihatemoney.org/ for daily spendings.
Later we moved that onto Nextcloud, using the Cospend app, which worked really well. You can also define a 60/40 division.
There is an FOSS Anfroid App, Moneybuster, that syncs with both of them.
Hi,
I've used MoneyBuster synced via https://ihatemoney.org/, to share it across a bunch of friends. But you don't need to sync - Moneybuster works perfectly fine on the device only.