From the root of your project try executing this:
vendor/bin/snappdf convert --html "<html></html>" g.pdf
If Snappdf is working, it should create a blank PDF called g.pdf if it fails an error should appear. this will give us more clues.
it was successful and gave no errors!
As of right now I still have not been able to get V5 running with a logo, I have two installations one on https and the other on http, both using snappdf and on LAN. Snappdf is working properly, there are no errors thrown in either laravel logs or nginx, and the logo that was uploaded is accessible directly by url.