It works depending on the feed, but remember, the first main use should be to describe the picture adding tags not properly capitalized (#OneExample) and links are NOT a good practice with alt text, because the screen readers won't read it properly

Also just did a small test, and it seems that tags in the alt text don't bring it up in search. Bit of a shame

I was more curious if it works at all, thus can show up in searches for said tags. Links are overall just not great for this idea, but having tags as alt text just seems like a good use of both tools while also keeping the overall post clean. Also, tags are case sensitive?