I’d suggest again reading the linked posts for tips on good and bad devices, and the role of routers.
IKEA Zigbee kit can be “weird” with extensions to the protocol for direct control (which can be a PITA using their cheap remotes and bulbs with ZHA). The cheap TRADFRI mains switches seem to work OK with ZHA.
Only you know your physical plan for router placement. Just think in three dimensions if you have more than one floor.