Could not found any.
Acebeam has something:
https://www.nkon.nl/de/rechargeable/21700-20700-size/acebeam-21700-5100mah-20a-usb.html
What do you mean by “internal”?
Initially I interpreted that as “built-in” but there are so many options that you probably mean something different.
yes, build-in inside cell.
Seriously? Do you know Google? It is a very good search engine. No, more seriously you abuse it, just a simple search and:
https://eu.nkon.nl/rechargeable/21700-20700-size/acebeam-21700-5100mah-20a-usb.html
By cons, I’ve never seen a 26650 with USB charging pice so I’m really not sure that there are any, good luck.
Ah, you mean a cell. I failed to notice which subforum it is and thought you were looking for a flashlight. 
There’s also 26400 from Fitorch. It should be possible to traplant the circuit to 26650.
MecArmy PT26 can be used as a usb powerbank, if that’s what you mean.
Edit - Ah, that’s not what you mean.
No luck.
https://www.google.com/search?client=firefox-b-d&q=21700+usb+charged+cell
Not ready to spent 20 EUR for this.
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Great, thank you Petr.