I have a rather dumb sounding question: Would spraying the front of my mask with Purell

[ProfessorGAC]

20. For Alcohol...

...mere contact time isn't sufficient.
Some mechanical action is required to actually remove the solubilized lipid from the surface.
Otherwise, as the alcohol evaporates, the lipid just seeks it's own surface level again.
If the lipid is gone, and there are enzymes present (unlikely on a fiber surface) any carboxyl groups in the protein can be transesterified with the ethanol. This effectively denatures the protein.
But, a little mechanical action removes the dissolved lipid, exposing the surface protein the oxygen. That's quite a slow denaturation reaction, but a little goes a long way in disrupting the virus' ability to reproduce.
That's why the lab efficacy testing for hand sanitizers involve a controlled friction source. Simulates the rubbing hands together.
Then the surface is plated or gelled for the challenge test. (Saw this done in their lab.)