You can check the System section of your Sonos account page to find out if your products are compatible with S2. Some products may not show what Gen they are, so look for Sonos S1 Required next to any products that are not compatible with S2.
I seem to recall that S2 compatible products relates to Connects manufactured after March 2015 - so ‘perhaps’ look for 1504 onwards at the start of the serial number on the unit, but that’s from memory, so you may need to corroborate this information by checking the information held in the assigned account.