If it's in a cold place, any heat will help, and heat applied to the soil is more useful for germination than heat applied to the air above the soil. Warm air tends to dry out delicate seedling foliage and, for what it's worth, moist soil tends to cool. If the pots are not in a cold place, a heating mat is unnecessary.

Warm water is surprisingly effective for heating pots that are placed in it, and will help humidify the air around them.

Check out this chart - that not only lists days to germinate at different temperatures, but the amount of normal seedlings as well. https://tomclothier.hort.net/page11.html

Good compilation. But what it is basically saying is that for most crops, if you're at 60F, making it warmer isn't going to help a lot, germination-wise.

See also

https://harvesttotable.com/vegetable-seed-germination-temperatures/

I am definitely at 60, 65 minimum. Most likely 70.