Can I use gloss paint on these?

If you clean them up very well I think gloss paint would do fine. If you are placing these outside I would use a paint made for outdoors. Thanks for saving him, he's very sweet!

Paint them with a couple of coats of PVU first this will prevent the gloss paint from soaking into the cement when dry paint with exterior polyurethane. Carol UK

I rather like your 'find' just as it is. 'Rustic'. Colourful plants will bring it to life.

actually, I like the 'natural' look; sweet! any paint you use will be subject to the 'elements' and peeling/fading/chipping ... concrete is porous .. you might want to consider a 'stain' that would penetrate the concrete -- https://www.concretenetwork.com/products-stains/how-to.html

https://www.hunker.com/13404408/how-to-repaint-yard-ornaments

i would say it depends upon how frequently you wish to repaint...if you don’t wish to repaint each year, I would use the correct (cement) paint for the job. Otherwise you would be penny wise but pound foolish.

Yes you can paint them with gloss paint. I would also paint them with a clear glaze coat to preserve the paint. Would give it extra gloss. If you use spray paint several light coats will get a smooth finish. Let each coat dry completely before applying the next.

I used acrylic paints from craft store on mine. then I sprayed with poly 3 coats and it looks great.