Figured I would drop this snippet in, having spent the time to develop it.
I needed a template showing FOR A GIVEN PAGE BUNDLE all pages by section, including both leaf bundles and page bundles. There are a number of posts that approach this via .Site.Pages, filtering by section, omitting page-bundles, etc. But they all work off the top-level section instead of subsections.
Caveat: This is not recursive, so it will omit sub-sub-sub-sections (page bundles in page bundles).
{{ $sectionIndex := -1 }}
{{ range .Sections }}
{{ $sectionIndex = add $sectionIndex 1 }}
{{ $curSection := . }}
{{ $allPgs := append $curSection.Sections $curSection.Pages }}
{{/* now get pgs of sections */}}
{{ range $curSection.Sections}}
{{ $allPgs = append $allPgs .Pages }}
{{ end }}
<h2>{{ $curSection }} <span class="small text-white">({{ len $allPgs }} pgs)</span></h2>
<ul class="list-unstyled">
{{ range sort $allPgs "File.Path"}}
<li>
<a href="{{ .Permalink }}" target="coursePage"
data-toggle="tooltip" data-placement="bottom" title="{{ .LinkTitle }}">{{.File.Path}}</a>
</li>
{{ end }}
</ul>
{{ end }}