While Picasa was nice for the casual user, it really sucked if you were serious about your images and their metadata. It caused me no end of problems, such as completely wiping out the MakerNotes for my Nikon if I used it too write data to the file.
I would think that Lightroom should be able to search things flash and lens. This Adobe forums (https://community.adobe.com/t5/lightroom-ecosystem-cloud-based-discussions/search-for-lenses-used-in-lr-cc/td-p/9571903#U11453860) post seems to indicate it should be possible in the desktop app, though I don't know as my copy of LR is very old.
Otherwise, you'll want to look into a better Digital Assets Manager (DAM) program. DigiKam (https://www.digikam.org/) is free and should allow you to do so. I think DarkTable (https://www.darktable.org/) also has some DAM functionality, though it's more aimed as a LR replacement.
IMO, though, the very best when it comes to metadata is PhoTool's IMatch (https://www.photools.com/). It is pricey and very complicated, but it gives you pretty much complete control over how you want to deal with metadata. For example
Hierarchical Keywords

Location data

Aperature

Lens

IMatch uses exiftool on the back end and can deal with just about any data that exiftool can extract.