AFAIK, most of the multi-crypto wallets are closed source. I've used magnum wallet and they're giving private keys for each of the wallet that you choose to have but it's currently suspended and I don't know when it will come back. The other multi-wallets that I used are coinomi and exodus but they're not open source, right?
How about jaxx? but it's also closed-source? correct me anyone.
ive used exodus wallet before and it supports multi coins and i think it gives you an option to hold your private key as well but i dont know if this wallet is an ooen source or not but will that be matter the most ? what if a wallet is open source but it isnt as famous or isnt as trusted as the other wallets that are not open source .
i check magnum wallets offcial twitter and the recent tweet was the suspension of the wallet . as seen here
https://mobile.twitter.com/Magnum_Wallet/status/1333472916588081154 . i never tried the wallet but it looks really great based on the description and based on the people that reply on that tweet . sad , wish they can come back asap