Many Polar watches work great with Stryd, but only records pace, power, distance and cadence. The other metrics are still stored on Stryd., you will need to complete an extra step after your run to complete your data (which is needed for accurate time predictions for events).
The best way to use Polar watches with Stryd, is to link the Stryd ecosystem to Polar Flow. Your data will automatically transfer from Polar to Stryd after your run. You will get the GPS map, power data, heart rate, etc. but not the advanced Stryd metrics such as vertical oscillation, ground contact time, etc.
To link the Polar and Stryd ecosystems, you can use this link and enable syncing with Polar (you can use the Stryd mobile app for this as well):
As soon as the Polar data appears in the Stryd system on either your phone or PowerCenter, you can complete your data.
If you prefer, you can forego the linking of ecosystems and always manually upload Stryd data. This works well but you will miss the HR and GPS data and is therefore not recommended.