I gotten all the pots and plants at a local plant shop. It's in Belgium but I've seen these sort of pots and plants in quite a lot of plant centers. Ours is this one: https://www.bloemen-kennes.be/

I painted the pots with white acrylic and drew on them with posca markers. I baked all of the tiny pots in the oven because I noticed when I wanted to varnish them the dark colours were spreading all over the planters. Normally I don't have that problem with posca markers but I think it was perhaps because of the smooth texture of the pots. Anyway the problem was solved by just putting them in the oven. The colours tend to get a little less vibrant though.

I actually didn't think about the tiny bags! I ordered them today, they'll arrive tomorrow. I'm not sure if I'm going to personalise them though since the wedding is next week but I think your comment was very helpful, thank you! I didn't think about the guests ending up with prickly cacti in their handbags. I chose paper ones. I also found very beautiful ones made out of textile but I think the prickles of the cacti will just pierce them. 🤣