[Trisquel-users] How can I check for compatibility before purchasing a new computer?

[tablet-user]

Hello. I am a free software user. My computer is out of service and I need to  
buy a new one (laptop). I have a list of candidate models that are locally  
sold (I can't purchase online, so Minifree computers are not an option). I am  
asking for your advice: How can I check if any of these models is compatible  
with free software and has no freedom-related problems (like requiring  
proprietare drivers or firmware, Intel AMT, etc.)?.

A acquantaince has suggested the Dell 15 5000, he says that it doesn't  
require any proprietary sofware. Would anyone please help me verify that?.

I have searched each model in my list in H-node but they are not listed and I  
searched with DuckDuckGo too but I couldn't find anything relevant. Are there  
other sites where I can check for compatibility (either the whole computer or  
the chipset)?.

Note: I am writing this from a borrowed Android tablet (hence my user name)  
and it is very difficult to write long texts like this.

Thanks.