I think that’s a 3.6 to 3.7 V cell. The XIAO gets 5V from the USB which it converts to 3.3V on board. But the on board converter needs some voltage “headroom” - I think it’s okay with down to about 4.0V but not less.
I wouldn’t connect the 3.7V directly to the 3,3V pin as you might blow it, but I think you could try connecting it via a silicon diode as it probably can run at 3.0V.
You might want to wait for someone who has tried this before and knows the answer for sure!