If the plan is ERISA-governed, no.
ERISA § 408(b)(1) “exempts from the prohibitions of section 406(a), 406(b)(1) and 406(b)(2) loans by a plan to parties in interest who are participants or beneficiaries of the plan” only if, with further conditions, “such loans [a]re available to all such participants and beneficiaries on a reasonably equivalent basis[.]”
29 C.F.R. § 2550.408b 1(a)(1)(i) (emphasis added) https://www.ecfr.gov/current/title-29/subtitle-B/chapter-XXV/subchapter-F/part-2550/section-2550.408b-1#p-2550.408b-1(a)(1)(i)
Otherwise, a participant loan is a nonexempt prohibited transaction.