And why would I trust a company I work at to be able to sign certificates for every single website on the internet? Especially if I need to install that root certificate on a personal device?
Because you already trust chinese, russian and a bunch of unethical for profit companies to do that?
As a matter of fact I don't. I'm keeping track of my root certs.
If you need such a device to do your job, maybe ask them to provide one so you can keep work off your personal device anyway? I disconnected my phone and so forth from work email and other services some time ago, and I'm not going back!
Why would you need to install it in a personal device? Just add an exception. It's still better than plain HTTP since you can check the fingerprint against your work PC, which already validated the cert.
Add an exception for every single internal site? You know how annoying that gets?