Just to put some numbers on this, we can assume that burning wood has plenty of particles in the 0.2-0.3 micron range, which is commonly regarded as "the most penetrating particle size".

N95 masks meet the standard that they filter out 95% of these particles. https://www.cdc.gov/niosh/nioshtic-2/20023155.html

In the following study, the better of the surgical masks that was studied allowed 25% of the 0.3 micron particles through, which matches the 1/5th effectiveness you mentioned. https://www.cdc.gov/niosh/nioshtic-2/00210276.html

On p16 of this EPA handout, they absolutely do mention the hand-holding logic of having a false sense of security. But they also address the possibility that the mask can make breathing more difficult, contribute to heat stress, and that these masks:

do not filter out harmful irritant gases, such as acrolein or formaldehyde, or other toxic gases, such as carbon monoxide

They also specifically state:

Masks can also be used in conjunction with other methods of exposure reduction, including staying indoors, reducing activity, and using HEPA air cleaners to reduce overall smoke exposure.

So I think the serious answers to your final questions are: it would help by 25%, I sure as hell would, and maybe?

I think an arbitrary kind of mask is effective for COVID-19 largely because of the fluid dynamics:

If the air has the particles you want to avoid evenly distributed throughout (as with smoke), then this model predicts you'll miss out on most of the benefit of a mask which does the appropriate filtering. So it's probably not worth using surgical masks for smoke.