I personally love Blink https://blink.sh/ it provides a great mosh client.
What I love about Blink is that it supports mosh and it includes tunnels, ssh-agent etc. out of the box (no need to install anything). It seems very well polished for the purpose of remote work. I have a mosh session open with our deep learning server in the lab 24h (works with network outage etc.).
I assume you can setup the same on A-Shell. Will play with it and update here.
Edit: spelling error
Registering for an account is free. you can get a signing key for testing (i.e. to build and run on your own device) for free also. You only need to pay if you want to publish to the App Store.