Why do you really need this ?
Why not just set up a VPS and deploy the NginxProxyManager to it together with a wireguard tunnel to your home system.
You really dont need 2 proxies…
Or if you want to keep the NPM localy on your home server, then you just setup wireguard on VPS with NAT and port forward to your tunnel.
My lab is around 65-70W, thats Router + Switch + Server (Ryzen 3600 + 3x 3.5"HDD)