They push Pocket more than Send, it seems, and as far as I know Send is actually built by Mozilla, and Pocket isn't. (Someone correct me if I'm wrong).

Both are built and run by Mozilla. (Pocket started out as a separate company, but then the whole company was bought by Mozilla). That said, Send is the right thing to use here, not Pocket.

>The files are sent P2P

afaik they're uploaded to s3, not sent p2p.

Correct. Though they are client side encrypted and the key is never sent anywhere.

Signal is also an excellent p2p e2e encrypted file sharing service.

Tox. A proper p2p messaging tool.

IIRC Signal needs phone numbers.

So Mr Manafort should chose Tox over Signal in any future crimes.