Have you also tested proton with the native wine?
Yes, I have a native Wine build from https://github.com/ValveSoftware/wine + steamclient.so working through my glibc shim since November (still need to commit the corresponding changes to the shim). There are some limitations, but overall it's quite feasible. However, it requires manual setup and there is no way in hell the necessary bits are ever going to be in the Ports, so this method is not for everyone.
I'd assume this should work better than the linux emulated one?
You'd be surprised. Wine's amd64 FreeBSD port receives almost zero attention, so it has some really annoying showstopper bugs, which Linux Wine running under Linuxulator avoids.