As far as I know two features are missing in the mobile version of electrum. One is coin control and the other one is signing/verifying messages.
My guess is that OP won't need those two. His coins are stored elsewhere, and if he is planning to only use the mobile wallet for his P2P trades, he will make one transaction and send those coins to the mobile wallet. There is now one UTXO there and hence no need for coin control. The only exception is if he agreed to make two or more deals with multiple people at the same day or around the same time. Electrum could potentially connect his UTXOs since there are is no manual coin control option available.
Signing and verifying messages isn't needed for OP either
Yet I can be able to use address freeze on mobile Electrum, but just not flexible and useful up to using coin control.
If you think about it, it's sort of the same thing if your Electrum app doesn't have many UTXOs. If you have 2, just freeze one, and Electrum will spend from the other. If you have 4, freeze the 3 you don't want to spend from and the one that is left will be used in your new transaction.