Mycelium is an open-source and mobile-only Bitcoin wallet. Mycelium currently only supports Bitcoin, ETH, ERC-20 tokens, and FIO token. In some ways, Mycelium is quite similar to the Electrum wallet with some of the differences being that it is mobile only, has a more refreshed user interface than Electrum, and also has a built-in exchange.
Mycelium, like Electrum, is one of the earlier wallets in the space. Also like Electrum, you can set custom transaction fees so you can choose how long you’re willing to wait for a transaction to be completed.
Mycelium also has a few more interesting features such as hardware wallet support, which allows users to hold their Bitcoin in an offline storage device while still using Mycelium’s user interface to see their holdings.
More information:
https://www.investopedia.com/best-bitcoin-wallets-5070283