So that setup effectively gives you an all-ports available connection (except 22) from your mobile device and anything that connects through it, like a laptop? The exit node would be the VPS.

Could I skip the home router and EoIP+VPN directly between mobile and VPS, for instance?

I am in a situation (restrictive firewall on ethernet/wifi, prefer personal mobile connection but it’s cgnat or something equally crap) this could be very useful for me.

What’s the recommended way to measure power consumption? Any instrument in particular?

Happy customer for years. However, they recently changed their price schemes. The cheapest plan (1 EUR monthly) no longer allowes custom domains, you need to pay more for that.