For a 120 sq m home you do not need mesh. Just buy an Asus RT AX86U Pro. Very solid router. It can easily cover your home. And it has Asus mesh tech built in …. So if you ever bought a second Asus router, you can easily create a mesh network with the two.

If your home has cement walls then the wifi signal has problems to penetrate that. A mesh router does not help with that. But since your home is only 120 sq m, just a single router should be enough

I have an older Asus RT AC68U and it easily covers my 200 sq m home. But my walls are wood frame and not cement.

If it is an older house, it may not be too difficult to run Ethernet cable either below the floor or above the ceiling to a more central location. Then you could either 1) add a more capable wifi router (and turn off the Xfinity wifi), or 2) add another access point at the new location to provide a better wifi coverage.

Very old homes, sometimes have lots of plaster in the walls and that is problematic for wifi penetration.

No technical barrier here. For $10 you can see if it meets your needs

I just want to trickle some water to some plants once per week. All I need is an outlet that can control the source power. It is a request from my wife so they do not perish while away.