Don't. Just fucking don't. Keep your personal stuff off your work equipment and vice versa. I don't know why people keep wanting to do this, because it only leads to trouble.

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.

Personal stuff on personal devices.

Company stuff on company devices.

Never mix. I don't even check my personal email on my work laptop.

If I need access to my home, it's through an external connection like LTE.

You wouldn't do this with a stranger's device, so why insist you do it with your employer's device? Just don't.

If you have a workstation and want to use the same monitors/headsets/peripherals with both the company device and your personal device try one or two KVM switches.

Don’t. And beyond that if you use their WiFi, connect to a VPN. Best just use LTE.

What you are wanting to do is likely a misuse of corporate resources. If you are still unsure go talk to IT

Use a tails usb

Preferably just dont though

If it boots from USB, boot a different OS. But overall, preferrably use a different device.

Just run portable Firefox without the root cert?

The computer probably has local security tools (such as an edr) that spy on you any way.

You need to assume it is completely compromised.

But... assuming this isn't in violation of your company computer usage policy (which it very much might be and can put you in trouble) you can install any VPN (avoid spyware shit) and a different browser (ideally something a bit obscure, like librewolf) and this will bypass the MiTM as the the device that does the MiTM would be either:

A) a network device that hijacks the HTTPS requests (VPN bypass this)

B) the browser used by the company

C) some other kind of software that atteches itself to all browsers via admin installed extensions (obscure browser might not be recognised by such software, be sure to check the installed extensions after letting the browser run for an hour)

And once you are done you can check the certificate chain in the browser to confirm.

Don't use the company laptop, you can only confirm what is going on with your own devices

Use your company laptop for only work....

If you install non-approved software you will probably get flagged by the security team.

What I did is use a ssh tunnel and rdp over that. ssh and RDP are both build in to windows. VPNs often don't work because some software needs to be installed.

Either double-fist with a second laptop or install QubesOS on your laptop