You still have to strip your thermostats off the wall. The best is still to not buy any device that is meant to last more than 5y that relies on a service.
how about something like - if the product needs to be uninstalled to be returned the company needs to provide for uninstalling the product from the purchasers location and shipped back to the company, with full payment of shipment and uninstallation provided by the company.
You say that as if it's hard to remove.
It can be hard especially if you don't have a replacement just lying around.
I'm sure I'm missing something, but in the past when I've replaced thermostats it's pretty easy. Easy to find a replacement and easy to do the work. I know that everyone has different levels of skill here but this is less involved than, say, replacing an outlet.
A replacement compatible with the heating that may have been installed 10 years ago by a company that went out of business and from a manufacturer that also went out of business.
There are a lot of people who are going to own nest devices that they had professionally installed, as many of these purchases push for using an on-site technician service to install for you (try buying any of the smart thermostats on Amazon, they all have an option for professional installation).