Never also taught about this, but thanks for bringing it up; we have to try that out too. My previous trust wallet was multi, but I don't have any altcoin balance on it that I can remember. I use Metamask for altcoins, but I will have to try this out some day, and for the part of it not having a sign-in message option, unless there is any need for it in the future, if not, I don't think I will need it for now, and if need be, I will look for a way to cross that bridge.
If your current portfolio has only Bitcoin then Electrum is enough but as stated move the funds to freshly created wallets never import wallets from addresses that are created by the closed source wallets. Metamask is available on Android too but I guess it's not that great cause you can see people complain about bugs and crashes in the reviews section. Whereas Unstoppable wallet is great compared to others but it may take a while to get used to it due to different UI and for the record Theymos even recommended it.
If you have a large variety of different crypto assets that you need to store, there's
Unstoppable wallet.