This has been reported for possibly being unreliable fact/source. Israeli source claiming it already happened: https://www.timesofisrael.com/iran-and-saudi-arabia-hold-joint-naval-exercise-in-sea-of-oman/
China did broker a peace/reconcilliation between KSA and Iran earlier this year. At the same time, US has promised KSA nuclear weapons if it stays onside with Israel's genocide more recently, even as it pretends to advance ceasefires that KSA positions to support.
KSA's alignment is not 100% to US empire any more, even if this announcement embarasses the empire.
Spoolable FRP pipes up to 4" in diameter can fit on a truck. Rated for 200bar. Pre covid, this was quoted as $50k/km as full deployment cost with 10s of km per day buildout rate. Spoolable pipe that can fit on ships has no diameter limit.
I don't know details of manufacturing process, but spools, plastic pipe extrusion, and fiber reinforcement should be highly automatable.