If you picked up your endlers with a batch of feeder guppies, then you can probably be 99% sure they are endler-guppy hybrids. Like you said, they are still quite beautiful, it's just important that in the future should you sell or give them away to anyone else, you need to inform the recipient so that they don't put them in the same tank as pure endlers and thus dilute the bloodline.
And I definitely wouldn't put any endler or guppy, male or female, in any shrimp tank if I was wanting to breed the shrimp, as babies will be toast.
And I definitely wouldn't put any endler or guppy, male or female, in any shrimp tank if I was wanting to breed the shrimp, as babies will be toast.