SSH agent forwarding was merged 3 months ago (after the patch waited 7+ years in one form or another), but per https://unix.stackexchange.com/a/437299 → https://github.com/mobile-shell/mosh/issues/337 (2012), mosh does not yet officially support port forwarding, despite https://github.com/mobile-shell/mosh/pull/583 (2013 → 2015 → 2017). It appears the initiator of the original patch has maintained their fork: https://github.com/rinne/mosh (disclaimer: I don't use mosh and have not tried or reviewed the differences from the official version).
Perhaps https://github.com/MisterTea/EternalTerminal is a viable alternative. Per https://github.com/MisterTea/EternalTerminal/issues/473#issu..., 'Several security teams have reviewed ET.'
SSH agent forwarding was merged 3 months ago (after the patch waited 7+ years in one form or another), but per https://unix.stackexchange.com/a/437299 → https://github.com/mobile-shell/mosh/issues/337 (2012), mosh does not yet officially support port forwarding, despite https://github.com/mobile-shell/mosh/pull/583 (2013 → 2015 → 2017). It appears the initiator of the original patch has maintained their fork: https://github.com/rinne/mosh (disclaimer: I don't use mosh and have not tried or reviewed the differences from the official version).
Perhaps https://github.com/MisterTea/EternalTerminal is a viable alternative. Per https://github.com/MisterTea/EternalTerminal/issues/473#issu..., 'Several security teams have reviewed ET.'