Hello

Is there is a software or solution out there for archiving the raw FITS and may be processed images? currently, I just zip them and save them on an external HDD...

I just zip them too and have extra info in the parent folder name (date, location, camera, mount, filter, number and length of exposures, object, etc.). Saves 30-40% of space. Tiffs don't zip well.
I catalog and tag images (end result jpg files) in my preferred media managing software (JRiver Media Center).
After that, for me it's pretty easy to find any object I shot and where the data is located on my computer.
Also a very useful tool for me is Everything (very efficient search tool by voidtools.com).

870Gb (not counting star timelapses and random DSLR star shots) of astro data since beginning of 2019. And I shoot OSC.

I found and currently evaluating the "Observatory" application codeobsession.com

It doesn't do the archiving part (I guess everyone just stores somewhere), but it does cataloging and tagging images for future search. I still have difficulty using it, but it is the only one of its kind that I can find (on Mac only)...