Yes the Monterey m/c and the Ventura one should see the same photo library if it's in iCloud and using the same iCloud user login. In fact I'm looking at two Mac session finder windows right now, one on an older rMBP with Monterey 4.5 and the other on a newer Mac mini with Ventura beta 4 on it.
The contents of their respective Photos folders are identical. I'm sending both desktops to iCloud, and the Photos folder is on both desktops.
Maybe Family Sharing could be useful here if y'all have different iCloud accounts. I haven't had to use it since I only need one iCloud account.
Keep us posted, I'm still trying to get my head around iCloud. In fact, I have no idea how I stumbled across syncing files across multiple Macs like this, it just started working while messing around with iCloud.
I think it's the future of computing actually, barring any major FUBARs