This Sonos support link below outlines whether a Sonos device is capable of being used on S1 only, or S2 only, or if a device is ‘hybrid’ and can be used on either system:

https://support.sonos.com/en-us/article/sonos-s2-compatibility

To create an S1 Sonos sysytem you need an S1 only device (not a hybrid product). Once a system is initially setup using the S1 App only, you can then add further S1 only devices to the setup via the App. You can also add hybrid products to the system if they have previously been used on S1, or if they have been used within an S2 system, but in the latter case you must first downgrade the hybrid device from S2 to S1 using the instructions in the following Sonos Support link, which requires an S2 App in order to complete the necessary steps. I also recommend the device to be downgraded is first wired to the router. Anyhow see this link:
https://support.sonos.com/en-us/article/downgrade-a-sonos-product-from-s2-to-s1

If all your devices are S2 only, or hybrid, products, then you’re best to use the S2 App and to create/use all on an S2 Sonos System - an S1 system-network requirements will happily support an S2 Sonos setup. There’s nothing to stop a user also having both an S1 and S2 Sonos system on the same local network, or operating both the S1 & S2 Apps from the same mobile controller device, which needs to meet the requirements stated in this Sonos support link:

https://support.sonos.com/en-us/article/sonos-app-requirements