If there is *any* installed software, assume your company will be collecting some data.
If you don’t have any installed software, and you want to be 100% sure, you can always re-install Big Sur from scratch, as if it was a new computer.
I don’t know in which country you are, but in many countries data collection by an employer from their own supplied equipment is perfectly legal. Indeed, it is to be expected.
That‘s why during my employed working life I’ve always kept separate devices for work and personal use.