I tried to use a different folder for the resource packs so I could store them elsewhere and then use a symbolic link to the resource pack folder but Minecraft doesn't see zip files within the symbolic linked directory.
This wouldn't really be relevant, except that I am in the process of stitching a bunch of resource packs together so its nice to be able to test them after I make an edit.
As far as I know, there is no way linking another folder to the default resource pack.
But you can make a folder and paste all your resource packs in it.
You can save the current resource pack folder on your desktop and when you are done testing your new resource packs you can get them back.
After you did it just move the folder into the .minecraft folder and replace the current resource packs folder.
You can absolutely replace the resourcepacks dir with a symlink to elsewhere. I don't use the official launcher, but that shouldn't matter as Minecraft scans it during runtime.
This is especially helpful because you can click through the warning and force old packs to load, without needing to make a copy for each Minecraft version. Packs as old as "pack_format": 4 (1.13) could theoretically work on any newer version (to 1.19.2 at time of writing).
Note that there do seem to be some limits on using symlinks. While the resourcepacks dir and any .zip'd or unarchived pack can be symlinks (or symlinks to symlinks), and so can some dirs in unarchived packs, texture files cannot be, nor can /assets/minecraft/textures/*. They will silently fail to load, as though the pack did not override those files. (For custom model textures, there is the same missing texture warning as for nonexistent files.)
