Gridcoin (GRC) supports scientific computations with BOINC. Coinomi wallet was one of the option to store GRC but there was no staking option with this wallet.
Now GRC is being delisted and action has to be taken. Here is an announcement:
https://www.reddit.com/r/gridcoin/comments/iu9vsd/psa_coinomi_wallet_delisting_gridcoin/
There are 5 options available:
Official wallet- it is probably the best option but is not available on Android, installation requires some technical skills and may not be straightforward.
Discord server where you may also aquire some GRC for free (type %get to the bot). GRC staking is automatic and can be checked by typing %stake to the bot.
freegridco.in - GRC hourly faucet that pays 5% APY daily, has a wallet to send GRC to, but no private keys available.
Microgrid wallet, I have not tried that and it maybe a bit insecure, but maybe suitable for small amounts and there is simpliest way to earn GRC by computing science in a browser (not good for Android due to page reload)
Hollytransaction wallet is a very simple and nice looking wallet with automated staking of GRC. BUT no private key shared.
Hollytransaction wallet has automated staking option for 3 more coins including PIVX that can be obtained for free with Pipeflare faucet.(along with ZEC and DASH).
So this is time to move GRC from Coinomi wallet elsewhere. If you know more options, please feel free to comment below.
Nice