The are some free apps for android and I guess apple with names like WiFi analyser. You could install one then delete it after you do your trials. I have a Fritzbox router from zen so bought a Fritzbox 3000 mesh repeater, it's excellent as I'm sure many others are. Plug in, press a button, job done. Whatever device you are using just follows the best signal as you move round the house, and all firmware updates happen at the same time as the router with no human intervention. We have a 5 bed L shaped house, the router at the back downstairs does most rooms and the garden, the mesh repeater in a front room upstairs does the rest plus the garage workshop and the cars in the drive, mobile signal is rubbish here so its handy that the phones are still on WiFi when you it destinations into maps. Why not start with 2, a router and a mesh extender. You can always add later. I'm not too bothered about theoretical maximums. I can stream 4k tv and use phones ipad laptops etc anywhere and that's good enough for me.