If foo has a Texinfo manual (GNU tools like bash usually do) then you can try `info foo` and search the index with i or I for -p. Texinfo manuals also have hyperlinks you can press enter on.
info is a greatly underused system and I'd recommend any *nix users to spend some time learning how to navigate it.
For bash: 'i' gives me "no indices found" and 'I' says "no index". I can do a '/' search, which finds some "-p" strings, but "n" doesn't work to find the next.
From some other comments, it sounds like "info" uses emacs at its core? So I suppose I'd have to learn some emacs commands, if that's the case.
info works without emacs, but some people prefer emacs' info viewer to the console one. The console viewer does have some idiosyncratic keybindings - for example, "n" means "next node at same level", and "}" means "search for next occurrence". "H" will give you a quick overview.
I'm surprised indexes aren't working for you - unfortunately I don't know of any suggestions to fix that.
I get that they may be unfamiliar, but learning your system’s tools will pay off over the long run. Search facilities in less and info are generally much more powerful than in your browser.
"If you are a bash newbie, you should read the bash manual. If you want proper search for the manual, you should use info. If you want proper use of info, you should use Emacs."
info is a greatly underused system and I'd recommend any *nix users to spend some time learning how to navigate it.