I've worked in several in larger/Fortune 500 companies, including one where the desk setups were handled by a labor union, any changes required multiple approvals, and DIYing anything (using personal equipment or even adjusting the existing desk position or height) was a rules violation and prohibited. You wouldn't be able to get past security with personal equipment larger than what could fit in your pocket, and carrying so much as a monitor or laptop that didn't have a company barcode on it already would get you stopped.

So yeah, these sorts of workplaces exist and thousands of people have to contend with their on-site limitations.

Besides the sibling comment, here in Germany it is common to have electricity certifications on equiment done by external companies.

If managed to bring through securty some stuff that you plug into the office network, isn't certified and something goes wrong, short circuit or whatever, it is on you to deal with whatever might happen including dealing with the insurance company.

Doing work on a personal laptop is unlikely to fly. Nor is swapping out a desk without getting permission.