I use alpha wallet [1] for ethereum + evm stuff.
I also make use of the Metamask wallet. I don't know if they are open source, but it's been part of the oldest wallet I have been making use of in the past, and there is no problem. It has both desktop and mobile compatibility, but the desktop version has more features built into it than the mobile version.
You can use kiwi/lemur/mises on android or if you are on iOS you can orion browser (I don't have iOS so idk how well it works there), on android at least metamask extension works as good as desktop.
Alternative application option is Alpha wallet available both on android/ios, open source, repos can be found on website [1].
[1]
https://alphawallet.com/