I highly recommend https://wefwef.app/
You don’t even have to download it, it looks almost exactly like Apollo. But there’s a bunch of other apps that look like RIF, Sync, etc. to make the browsing more pleasant and usable/familiar.
I believe any accounts joining the family need to first have a Google Payments profile in the country the owner of the plan is in before you can join. Or is that not the case anymore?
There’s an icon in the top right to sort