FYI… you can connect up to four speakers to each Amp (or six speakers using Sonos Architectural by Sonance speakers). And each Sonos Amp acts as one zone, meaning all speakers wired to a single Amp will play the same content at the same volume.

if you have 2 amps and 5 rooms/zones, why would you need a 6 zone speaker switch?   You would want to have 2 smaller switches, or 1 4 zone switch for Amp 1, and Amp 2 doesn’t use a switch.

Also, not sure why you’re including a theatre room, as those normally have their own system.  if you don’t want to use Sonos for that, you could use a Port to integrate the existing setup with the rest of your home.

Lastly, the ability to play different sources at different volumes in different rooms through the Sonos app is a big part of what you get with Sonos.  Although I understand the need to use a speaker switch for budget reasons, you’re not getting the best experienced this way.  Having gone that route before, I wouldn’t do it again.  I would either plan on more amps when the budget allows, or use Sonos speakers instead of amps..