I have no idea if this is what the OP is referring to, but it's pretty much impossible to use HTTPS on your home network without managing your own Root CA and somehow managing to get certificates signed by that Root CA into your devices.

You've got a fighting chance in a corporate network where you can deploy and manage the Root CA via Active Directory/Group Policy, but managing it at home with consumer-grade devices... not gonna be a good day.

I'm not sure what the original commenter meant; however TLS is useful only when talking with your own server. What about other connections? NTP, DNS etc are all unencrypted (read: unsigned). Google "DNS client CVE" for instance. Or what about SSH? It may not be accessible from the Internet, but still exploitable from an infected host in the LAN. Someone has to keep all that software updated. In those conditions, I would never connect a RaspberryPI or similar to my door / gate / car / ...