Upgrading my primary WiFi router in existing HomeKit home

I have been running my smart home through a 5th generation AirPort Extreme in bridge mode and 2nd generation AirPort Express extending the wireless network. I have multiple HomePods (3 minis and an OG full sized), an Apple TVHD, an Honeywell thermostat (it’s now Resideo), a couple humidifiers, and several Meross bulbs and switches.

There are 4 of us in the house and we have a number of computers, iPhones, and iPads. Lately I have found that the WiFi 4 has just been slow (especially when multiple people are streaming content) and the AirPorts have been dropping devices so I want to upgrade to a Linksys WiFi 6 mesh router.

How do I transition my smart home over to the new router?

Can I simply plug my new main router into the IP gateway and use the same Network name?

Can I use the same SSID for the main router as the Extreme?

Do I need to reset each device to the new network after setting up the new router(s)?

Should I just start from scratch and set up a new network?