Not gonna lie, I have been subject to this kind of bullshit before, looking for a niche use case but ultimately just wasn’t suited for the role because the software I was using had a load of other drawbacks that came with it because of the way it was designed to be used. And usually I don’t like the way they like to use it
I used to use ‘mu’ a lot. It paired well with its extension that you might be able to find easier in a google search ‘mu4e’ (emacs), but it uses an xapian database for easy and fast queries. It was designed with the enormous amounts of email people receive in mind. Pairs very well with offlineimap. No easy (unless you like using termux) android use. Should be available on mac, however I don’t have a mac to test with. Should work with windows as long as you are okay with the WSL.
Before I forget to mention, it is a cli based application but I found it to be amazingly efficient for local email handling and search.
God tier search