Wyze cams are pretty good and inexpensive. Add a 64gb SD card and set it to alert you when it sees a person.
Need to have WiFi connected to them but you can keep an eye on things when not around. Even has pretty good night vision. Hard to beat for $25-$30.
Are the Switzer boilers still available? They are like a Garn but pressurized.
Econoburn also sells a indoor type gasser in a prebuilt sheet metal enclosure.
They’ve become quite popular here in NH. Been thinking to get one or two to supplement my wood boiler in the shoulder seasons...hard to get contractors to even return a call.
because Christmas is just around the corner...no Texas button? No problem...less than the cost of a port job from a Premier Online Saw-porter.
Only 70 left.
https://pullstarters.com/
For a guest house (occasional use?) I’d probably go with a gas on demand tankless.
But I really like the heat pump electric water heater I have for my place.