I have my fritzbox connect to the ONT in the garage. It provides pretty decent wifi speeds to
70% of the house. I have an Ethernet connection from the garage to the other side of the house, wondering if I can have some sort of mesh/repeater setup with a second unit via Ethernet connection to the base router.

Happy to look at other brands/models as a solution.

Just setting up a second fritzbox as a wifi mesh unit would be fine but just wondering if I can utilise the Ethernet port at the other end of the house or not.