I can select a folded section using the mouse / trackpad and it will select the header and hidden content. The key to doing this is selecting the ellipsis after the header (which seems intuitive enough).
However, I cannot do the same using the keyboard alone. Keyboard shortcuts always end up expanding the fold once it gets to the ellipsis. This includes the Shift+End shortcut. The Shift+End shortcut works, however.
Here’s a video: Obsidian select fold "bug" - YouTube
Would be great if we could select the ellipsis with all the regular selection shortcuts and/or be able to assign a hotkey to select the current line, which would select the line + content if the line is folded.