We deal with it my having cars with heat.
In fact my minivan has heat in it 24-hours a day. I have equipment in it that can’t be allowed to freeze or it will cost thousands.
Fix the heat, if you don’t know how, find someone that does. Heating systems in autos are really a simple thing. Doing a search on the net should lead you to a forum for auto repair that people can help. Also here in Toledo, every weekend there is a call-in radio show about auto repair problems. I would guess that most cities have one of these, call the local radio stations and ask them for the times it’s on the air and the phone number. Then there is also the local library, go get a book on auto repair.
Pay someone to fix it. If you don’t have the money, learning is free with the methods I pointed out above.
It would be fairly dangerous to drive a car with no heat to clear the windshield.
Many years ago I had a 1969 VW Bug, it did not have a lot of heat, but it keep the windshield clear. I made a very good supplemental heating system for it that worked well, in fact it was the warmest auto I ever owned.