To my defence I did not realize right away you were the same person, at least you can see I am consistent in my answers. 
So, if you want your users or yourself to browse vignettes
- I think adding a pkgdown website is 100% worth the effort. Also because it allows you to add custom grouping to the reference. And because it means all the docs are browsable without installing the package.
- From GitHub you can write the line that the users would need to type to install the vignette. Yes you just need to have the vignettes in vignettes/ as created by e.g.
usethis::use_vignette(). Also, be careful to list all vignette dependencies in DESCRIPTION (as Suggests if they are not used elsewhere).
remotes::install_github("owner/repo", build_vignettes = TRUE)
As far as I understood, browseVignettes uses the vignette index of the installed package so vignettes that are in a doc folder.