@guillaume how does it solve the problem? Nord's Meshnet allows to create a private "sub"-VPN for all of the devices in it (typically your own devices), accessible via the internet (only for devices using NordVPN obviously). It's like LogmeIn's historical software, Hamachi.
Also, what if a router doesn't have a VPN function?
This is not a solution.

Now that Wireguard is also used in ProtonVPN's client, a meshnet-like feature should be even simpler. ( Nord's meshnet is based on Wireguard: https://nordvpn.com/blog/achieving-nat-traversal-with-wireguard/ )

You can solve that by setting up your router as a VPN server and use Proton VPN on the router VPN client function

This is the ONLY feature keeping me with Nordvpn at the moment. It's extremely useful, even simply to connect to YOUR other devices.

Possible alternatives i've thought about are:
- (to connect any device) using a service like zerotier or hamachi to create a vlan, but as stated this is a problem on mobile devices, and in general, i shouldn't have to rely on a third party service to do this
- (to connect your devices) setting up forwarding on every router your devices are connected to, for any port you need. This is obviously problematic for a TON of reasons: 1) You have to setup some form of dynamic dns, again, relying on third party services. 2) You may not have access to the router settings. 3) You are limited to the forwarding options the router offers. 4) The router configuration may be cumbersome. 5) The safety of the transmission over the internet then depends entirely on the service/protocol responding to the traffic of each port, unlike a mesh accessible ONLY through an already encrypted vpn. 6) Opening up ports can be risky if not done correctly.

A secure alternative would be accessing everything via SSH tunnelling: in router settings, forward a single public port to a device running an ssh server, and create an ssh session with as many tunnels as you need. Again, this requires access to the router, it is cumbersome and unpractical, has to be set up on all of your devices, requires an external tool and additional knowledge, etc

I agree. I currently use Nebula and have been considering Tailscale, but it would be great if this functionality was built into ProtonVPN given I am paying for Proton anyway. My usecase is pretty simple -- I would ideally like to use a little Mango travel router to access my Jellyfin server; given the travel router already supports ProtonVPN that would make my life a lot easier.