XnView Software

I store my photos in folders like 2011, .... 2021, 2022, etc. inside are each event etc.

I like using "show files in subfolder" to find a photo I know is in a year

But what if I want to do this for a few selected folders, how can I do this?

If the goal is to find a photo, I'm using some tricks.

In yearly folders, my subfolders are structured by events, as follows : 2022-11-07 beach hollidays
I added a category "folder" to all these subfolders

In "Categories filter" tab, I select "folder" , to get all events

Then I type some digits in quick search field , such as 201 (for years from 2010 to 2019) or -07- to select July in all years , or some words (holiday)
I can then see at a glance the events for which I forgot the exact date. (or events that I know there were in July, but forgot the title)

It's not not an answer for your request, but it can help ...

I have the same folder structure as you, but it's not useful because under each event folder I have more folders (raw, jpg, video) before I get to the photos. So when I see all these folders with the names in them all I have is blank folders instead of icons of the things inside.
That's the biggest problem I think.
https://imgur.com/a/OZ3RRC2

The browser is mostly useless to me, I have to read each word. I wish it showed the photos of subfolders like windows does.

Other tips :

Tools > Find
- First field empty (or *.jpg)
- Select root folder in 2nd field,
- Match all (multi criteria)
- Recurse subfolders,

Add one or more conditions ...
Examples
Pathname contains 2011
Pathname contains 201 (ten years...)
Pathname contains -07- (if you want to select July)
Pathname contains holidays (events)
Pathname contains jpg
Categories > Birds
...

> Browse

well not exactly
Say I have folders A-Z.

Maybe I want only A,E,T,Y
it's not the same root.
But a selection.

Yes, your request is clearly formulated. I have looked for workarounds

It is possible to quickly tag some folders in the browser. These "tags" can be left for permanent use, or easily removed for occasional use.
BUT when you select "tagged" in the category filter, you can't get the pictures of these sub-folders to be displayed...
( For information, I added the category "Folder" to my folders, to be combined with "tag" or other tips )

This could be an interesting feature to allow recursive display, I hope Pierre can investigate this possibility ( "UP" for this post )

More generally, when the browser contains a few folders as a result of a search or a category filter, (my folders HAVE categories), it would be interesting to be able to switch to a "recursive subfolder content" display for selected items.

(For my own use, I have stored my photos in a simple tree structure, and added also descript.ion files for folders, so that I can quickly find what I am looking for.)