Tor also, in the early days.
i don't think it matters that much, this isn't exactly a long list. qubes doesn't work on most hardware. wireguard is ridiculously elementary in what it does, literally just elliptic curve keys and ECDH, same stuff used here in nostr.
signal was probably developed by intels. it was originally called "red phone" and was the first chat system binding to mobile phone numbers and using the mobile network (SMS) as a back channel to pass shared secrets, iirc - or something like that, maybe it was just for a rendezvous.
TOR escaped into the public domain, and the Navy has never been able to put the technology back in the bottle. Signal’s obsession with correlated numbers has always been a red flag for me.
i built the majority of the implementation of a replacement for Tor that uses the HORNET/LN style client-side onion messages.
https://github.com/indra-labs/indra
i was in the middle of changing part of the design of the protocol to make variable length routing headers and still need to design a connectionless UDP protocol (tricky because of congestion issues) but my funding ran out... i've been wanting to build an agoric, monetised version of Tor since 2007 at least.
hopefully some day soon i'll get to finish the work.
there's a lot i can write about it but that was the most important stuff, with those two changes made and some funding to launch an initial caretaker org/foundation to return the initial funds to the investors the rest is designed to be a freestanding economy.
How are you solving the trust of payment issue