Dell offers no OS laptops and desktops but sadly only for business customers. Consumers have to buy the Windows adware. You sometimes see the enterprise stuff for sale second hand with no OS too. The only specific laptop I know that consumers can buy with no OS is the Framework Laptop, which looks awesome.
We just recently purchased Mail Assure with Cove Data Protection from N-able to achieve a similar goal, but unfortunately I don’t have any experience with it yet to advise if it is any good. It is an option though.