For home it's not that bad, but there could be conflicts at some point. Your clients will send data to the Internet unknowingly when dns is missconfigured.

It's better to use domain you control.

I'm a fan of buying cheapest to extend (like .ovh, great value) and use real Let's Encrypt (via dns challenge) to register any subdomain/wildcard. So that any device will have "green padlock" for totally local service.