Whenever a company is tracking such data, there is no way for users to know if collected data is used or sold for other purposes, now or in the future, so the default should always be to collect no data at all.
If you want to run UI/UX tests/experiments on users, just ask them (and maybe offer incentives to participate?).
If you want to run UI/UX tests/experiments on users, just ask them (and maybe offer incentives to participate?).