I use pancake, works pretty well. It’s paid, but only a one-time payment and you get the code.

EDIT: here’s the link: https://www.pancakeapp.com/

For baseboard heaters, I have the Sinopé line of ZigBee thermostats, with home-assistant on my home server. Baseboards are kind of particular in that you have one thermostat per room, so at 350+ for a Nest, it’d be cost-prohibitive as I have like 15 thermostats in the house. Also, they’re line voltage, meaning that they directly switch the full power of the heaters, so they need to be well made.

I’ve had my Sinopé thermostats for 2+ years now, and I’m very happy with them. No clouds involved here.