I'm not entirely sure about the technical differences but from my understanding VPN connections are preferred. From a security perspective, ssh has some more considerations since it's easier to detect it's open, and you should lock down root access and other privileged accounts. but SSH seems simpler to actually get working vs a VPN solution which would probably require a reverse proxy or something to get the TV working.

For example, compromising a ssh service gives you access to the shell immediately vs wireguard or similar that historically (from my knowledge) has had fewer critical vulnerabilities that could lead to remote code injection or access. This is also why many corporate and best practices recommend layering ssh through a private VPN like IPsec, OpenVPN, wireguard, etc.

in practice it's most likely fine as long as

• you don't use root or an account with sudo to do the ssh forwarding
• require a ssh key for all connections (at minimum any remote/internet connections)
• update the system regularly. you can automate security updates with unattended upgrades on debian-based systems.

ssh -L 1234:localhost:1234 remote_server binds the RPi's localhost:1234 to remote_server's localhost:1234. You want to bind the port to something on the RPi that the TV can hit, so something like ssh -L 192.168.1.5:1234:localhost:1234 remote_server, where 192.168.1.5 is the RPi's address.

I think you also want -N on the ssh command.