There are AFS servers for Linux. I don't know if macOS supports NFS shares, but if it does then that should be speedier.
That said my Samba server does saturate a gigabit connection with a Windows client. The CPU usage on the server is around 25% when doing so, with a crappy low end AMD dual core from 2013 so the CPU shouldn't be a bottleneck.
Yes, NFS shares can be (auto)mounted on OSX. It works well if you don't require authentication in the protocol. I have some devices setup this way on my LAN and the only "tricky" part is making sure your uids/gids align with the file perms on the server.
Is there any non-airgapped use case that doesn't require authentication?
NFS sounds great when presented as a "faster alternative to samba". As soon as anything else is said about it you realize there's a reason it's been a bad choice for 20 years.
> Is there any non-airgapped use case that doesn't require authentication?
Here's one: Say you maintain the devices in your home LAN/WLAN, and you would like to centralize the storage/access of certain data like photos, music, video, shared Keepass DB files, etc. Let's also assume that you don't have a local threat model in your home network that includes "highly technical people that know about setting their UID who wish to access files you don't want them to see or have write access to". I would argue this is a semi-common home scenario for many of us. Perhaps you want your SO and/or child to have access to shared files on a NAS which supports NFS, and you don't have any Windows endpoints to worry about.
In this scenario it's perfectly fine to just setup the devices which you want to have access to the NFS share(s) and completely ignore authentication for the file sharing protocol. If you're worried about WiFi guests that might be savvy or curious then simply create a guest-only wireless network that can get out to the internet but not the LAN.
In my experience trying to export AFS mounts from my NAS for TimeMachine is that it is a regular headache when Apple randomly breaks it.
Some patch will drop and suddenly my wife will be complaining about popups on her machines about failed TimeMachine backups and often I have to delete the entire backup and start over from scratch which takes hours and days, especially on the laptops that are doing it over the wireless.
That said my Samba server does saturate a gigabit connection with a Windows client. The CPU usage on the server is around 25% when doing so, with a crappy low end AMD dual core from 2013 so the CPU shouldn't be a bottleneck.