May pilots receive compensation for performing preventive maintenance under US regulations?
First, it's a little too broad to say that a private pilot can perform preventive maintenance. The full wording in 14 CFR 43.3(g) is (emphasis mine):

Except for holders of a sport pilot certificate, the holder of a pilot
certificate issued under part 61 may perform preventive maintenance
on any aircraft owned or operated by that pilot which is not used under part 121, 129, or 135 of this chapter.

In other words, a pilot can't perform preventive maintenance on just any aircraft. The definition of &quot;operate&quot; in 1.1 could be stretched, I suppose, but the pilot has to have some degree of operational control over the aircraft. Another pilot without that control couldn't do preventive maintenance on your aircraft anyway, whether or not you were paying them.
Beyond that, the word &quot;compensation&quot; doesn't appear in part 43 so it seems not to be a factor in who can perform maintenance, preventive or otherwise. And common sense says that a pilot can be compensated because otherwise a part 91 ferry pilot wouldn't be allowed to top off hydraulic fluid or replace a landing light bulb (for example).