The best thing is to use a different device, period.
Since the company is lord and master over the device, in theory, they can see anything you’re doing.
Maybe not decrypting wireguard traffic in practice, but still see that you’re doing non-official things on the device that are probably not allowed. They might think you’re a whistleblower or a corporate spy or something.
I have no idea where you work, but if they install a CA they’re probably have some kind of monitoring to see what programs are installed/running.
If the company CA is all you’re worried about, running a browser that uses its own CA list should be enough.