[rrr_oh_man]

https://github.com/postgres/postgres

Postgres (core?) seems to be 85% C.

[HaZeust]

He's referencing pgrx:

https://github.com/pgcentralfoundation/pgrx

To be fair pgrx was mentioned in OP under a positive light, and OP did say he likes avoiding coding in C, so it was something to bring up.