I'm looking for a way to access my computer network/computer outside my local area. I have NAT 3 forced by ISP. Currently I'm using VNC server that is capable of routing the connection through it's own servers, but I'm looking for solution to do the same for SSH and controlling microcomputers. I was thinking about VPNs, but that's more like a way to avoid region blockade instead of externally accessing LAN. The solution may be paid.
You can use tor network with "hidden_service" feature on the host you need to access. It is not require own external servers. Access is through the .onion domain zone and the torify utility on client host. Its free.
Not exactly what you are looking for, but it may be an alternative: AnyDesk