Yes, as long as the heater is a single-phase heater within the energy limits for the Mysa thermostat.
Energy requirements for Mysa for baseboards:
Mysa is compatible with most high-voltage electrical heating systems, such as baseboard heaters, fan-forced heaters, and radiant ceiling heating.
Power: 1900 W (Max at 120V) / 3800 W (Max at 240V)
Voltage: 120 V - 240 V
*Compatible with 208 V Single Phase Systems, not 3 Phase Systems
Current: 16 A (Max) on a 20 A breaker panel
Mysa is tested to UL and CSA standards through Nationally Recognized Testing Laboratories (NRTL). The NRTL certification is displayed on the back of the Mysa unit.”