Something like a raspberry pi or equivalent, and use reverse SSH set up to connect to a server with a known address on your end.
This means that ports don’t need to be opened on their end.
Also if you go with a gateway host, shift SSH to a randomised port like 37465, and install fail2ban.
Been seeing quite a few advertisements lately that are basically, “Gas is used for stuff”. Companies trying to make sure that governments (and the people who vote from them) keep gas infrastructure around for them, I guess.