Uberpay.io is similar to coinomi and i feel this is one of the better universal wallet ideas.
Based on the electrum wallet, the app/wallet will piggy back off (in this case) uberpay.io.
The app/wallet will interact with their site and you can manipulate your coins at your whim. You control your key data, and the app/wallet will create appropriate transaction data to reflect your directions, this transaction data will be sent to the appropriate block chain via their site.
You do not need to store any block chain data, and they should not store any of your user data so it's as safe as your own security.
Whilst it does require their site to be active, because you maintain your own key/addresses, in the worst case you can run and sync the full proper wallet to access your coins yourself.
are coins also staking?
Not at all. These wallets work by crafting transactions from data received re specific addresses, then inputing them into the block chain without having actual access to those coins.
They work in some ways similar to how a cold wallet might work, where the client that crafts and signs the transaction does not have access to the block chain - but in this case it does have access to the coinomi/uberpay api.
Only full wallets should stake, or specially crafted wallets.