Everything is allowed in NFTs, but not the way you think.
You just have a link to some data, which can actually be changed later on (not really secure, thus people use IPFS to make it a little more secure).
The NFT is only a certificate, it doesn't distribute any assets (images, videos, etc.) — if you consider this — it cannot be any other way, because it needs to be on the blockchain and it will bloat pretty fast if it includes anything other than a little bit of byte code.
Using Rarible to mint NFTs is pretty easy — a matter of filling some fields and providing a link to asset, but you are left with the limitations on their own smart contracts. Also note that it is actually somewhat expensive it varies quite a lot but expect to pay $35-150 for a single nft.