Hi,
Can you try following and see if it allows you enable Dual Sim Dual Standby (DSDS)?
Go to your phone dialer and type *#*#4636#*#* you will see a menu with three options click "Phone Information" click it and skim the page until you see Enable DSDS and check if the toggle switch is not greyed out and you can switch it on?
I'm planning to buy Surface duo so it would be helpful to know, if DSDS is available or not? DSDS was available from Android 10.