Glass lids =Guppies can really jump... they don't often do it, but they certainly can and will
You could always have a glass or perspex lid made, so it's not a big hood thing over the tank, looks more seamless, but keeps fish and shrimp inside the tank!
Guppies might pick off some shrimplets, but a full grown neo is way too big for them to eat. If you have a lot of planting and cave bits to hide in as well, most shrimplets will make it too. My shrimp colony doesn't seem to have suffered from sharing a tank with guppies, they're often recommended to live together!
There's also a gap between my hood and my tank (second hand, the hood isn't the one designed for the tank) and finding a shrivelled, dead red cherry shrimp on the tank stand one morning was very sad! I bodged it so it leaves less of a gap now.
"Hood" lids =
IMO