WireGuard limitations hurt the attempt however.

For example, multi-hop betrays the actual exit node to your ISP (or MITM) due to the port used.

To clarify, this is refering to Mullvad multi-hop feature. Doing your own multihop setup doesn't have this issue, right?

Correct. Note that the MTU will be further reduced and that WireGuard DIY multi-hop may be inferred.