Hi! Welcome to the forum. I don't have chinchillas so, I couldn't really say which has more work/less work. But guinea pigs, Should
not chew on plastic if you see a guinea pig chewing on the plastic take it out, because it can do damage. And they should have something to chew on, Like the all natural fiddle wood chews.
How many are planning on getting? Guinea pigs are herd animals and do better in pairs or groups, The bigger the cage the better for piggies(I.e C&C cages petstore cages are basically litterboxes they sit in). So they have room to popcorn, do laps/zoomies.(which is really cute to watch!) And floor time is a must also. Which is important if you have them in a small cage, the more important floor time is. the bigger the cage, is still important. Floor time should generally have a spot bigger than the cage it self.
And they should have veggies everyday, Romaine, red/green/yellow peppers, Parsley, cilantro, kale etc. (theres a food chart on here with tons of veggies/fruits for them) And for fruit apples,oranges,grapes, etc don't give them so much fruit it has to much sugar in them.
For bedding/ toys, I personally like fleece in the cage, you sweep the poos everyday. And they have cute prints! And change it every week like you would with bedding. Toys, natural wood fiddles are great for them to chew on/hide in. You can also make them snuggles/cozies. My girls like playing with a cat toy that has a bell in that i found at the 99 cent store, Or ping pong balls for them to roll around. And tunnels, paper bags.
For the pellets and hay, Do
not get them the pellets with seeds/ colorful bits in them. They are a waste of money and pigs do not care for them. And hay, You can order from small pets select hay, Or get some at your local feed store. And no treats with seeds and other crap in them. Good treats for piggies are fruits.
Sorry if its a lot to read! But hopefully I could help!