Any ideas for a hardware setup for small showcases or educational workshops? Small audio amplifier with a small set of speakers? Suggestions?
I see @madskjeldgaard is using small active studio monitors The Ones - Genelec.com?
Ouch, I also did check the price. 
Notes for setting up a Raspberry Pi 4 for audio work :: Mads Kjeldgaard — Composer and developer
I used to use Event 20/20 powered monitors for this kind of thing. They had a bit better bass response vs other things at that price point (there may be different models, but I had ones with verrrrry large drivers). And (at least in the United States) it was extremely common to find them used - at some point I think I had six in total, and I didn’t pay more than 100-150 per speaker, all second-hand.
Having said that, they’ll just never get that loud, so if you care more about filling a room vs fidelity, you might just get a low-end PA. It’s pretty common to find offers where you can get a pair of PA’s plus stands and bags to transport them at a modest discount - they’re larger than monitors, of course, but transportation-wise it’s still just two big heavy bags you can throw in the back of a car. I have a set of 15" PA’s and they’re fine to do a small-to-middle sized performance.
Let’s go cheapest / workshop mode first with a Behringer MS16. Using headphones would be another possibility, but I’m afraid of ear damage (I know there are limiters).