Yes, as others have said, you basically have a couple options to start with for pre-heating. None of which turn on the seat heater in my findings even though I think I read something in a manual at one point that sounded like it would.
#1 is "Go Times" which is what you want which will use only wall power for heating. As they've said, on 120V, it will only make the car a "bit less cold". On 240V it will work pretty well.
#2 is "Remote Start" which is what you did. There are options on your left menu you can change as far as whether it will auto turn on front and/or rear defrosters, attempt to get the cabin to 72F(I believe those are the defaults) or if you want it to just go with the last used HVAC settings, or manual defrost, etc... It will just attempt to get the cabin there using whatever means it has. So, it will be happy to pull the few KW available from the wall, then add another couple KW from your battery and fire up the ICE and burn some gas as well.
For Go Times, you'll set a time you want the car ready and it will start pre-conditioning 15 minutes before that time and continue for 15 minutes after.
For Remote start it will run for 15 minutes by default I believe(You can make the time shorter) and at least with the fob you can repeat that up for a total of 3X(so it if it's set for 15 minutes you can click the buttons 3 times in a row and it will run for up to 45 minutes).
Not sure if you can do more than 15 minutes using the app/web.
Also, if you haven't noticed, if you use the heater while driving to work, you'll notice your battery depleting significantly faster. Below around freezing it seems like it uses the battery about twice as fast for me.(cuts the range about in half) Well, in EV mode anyway. If you're running the ICE anyway you'll get more free heat from that.