Business & farm

So.., the compensation you paid to your self  (as a single owner LLC)  from PPP loan wouldn't be treated as 'income' and wouldn't be on Sch C.  Does this mean I can't use the 'compensation' to contribute to my self-employment 401K?   If the answer is yes you can, and say contributed max employee portion $26K (including catchup contribution), will I be able to contribute to 401K if I become W-2 employee later this year?