If the biggest issue is "we want to encrypt traffic" then the answer really should be something more automated. To put it another way, TLS certificates used to convey a lot of things. We had basic certs that said "you are communicating with the rightful owner of domain example.com" and we had EV certs that said "you are communicating with the rightful legal entity Example Org, who happens to own example.com" and so-on and so-forth.
But the thing is, we've killed off a lot of these certificate types. We don't have EV certs anymore. Let's Encrypt effectively democratized it to the point where you don't need to do any manual work for a normal "we want to encrypt data" certificate. I just don't understand what your specific requirements are, if they aren't directly "encrypt this traffic" focused, where you actually need valid certificates that work across the internet.
Put differently, if you're running an internal CA, you can push out your own certificates via MDM tools and then not worry about this. If you aren't running your own CA but you're implementing all of this pomp and circumstances, what are you trying to solve? Do you really need all of this ceremony for all of your devices and applications?