I’ve always used the web browser on desktop for it, also on Splitwise, so I don’t have experience with mobile here. But there’s an Android app developed by the same developer IIRC

Unlock more RAM with a monthly subscription, starting at 10 €/month for every GB we disabled for you!

I’ve used a wallet from Exentri for many years. I think they are Swedish.

Me and my partner moved from Splitwise to Cospend on my Nextcloud instance. I like it more.