I have a community center on the gallery if you wish to check it out. It works fine, though it's not the best example.
https://www.ea.com/games/the-sims/the-sims-4/pc/gallery/11D7941DB8A711EA84ED9BE9EBD29134?category=all&searchtype=ea_origin_id&sortby=newest&time=all&searchquery=crocobaura&max=50&maxis=false
As a rule, food stalls all work with this lot type, but some vendors may not show up if you have too many sims on the lot. Also, some food stalls have working hours and the seasonal ones I think only work during their specific season so they won't be open at certain times.
The university cafeteria also works and will summon a vendor on this lot type.
The sales table will summon all kinds of vendors, some will sell just one type of merchandise, like the MySims figures, candles, fizzy juice, or some will have a mix of everything like seed packets, candles, fruits, etc.
The painting displays will summon vendors, you can still buy paintings even if the vendor is not on the lot.
NPC sims will only tend to plants in planters, so if you want to use it as a garden center you need to add planters.
My suggestion is to add maybe 5 or 6 vendor type attractions on the lot at most if you want them to be all open at the same time. Even then some may not be open if there are too many sims on the lot, so you need to check what other attractions you have on the lot, wood working tables, fizzy stations, candle stations, garden planters, etc. as they also attract sims and a mentor.
