JR Central revised their ExPress Reservation notice section adding two lines of red text:
“From late October Apple Pay Suica can be used as the EX Reservation designated transit IC card.” JR Central will post more details at that time. At present Apple Pay Suica cannot be used with the EXPress system.
The JR Central/JR West EXPress system is a special EX transit IC card for Tokaido and Sanyo Shinkansen travel. EXPress members can transfer from regular train lines and board the Shinkansen touching a regular transit card in tandem with the EX card.
There is also a paper receipt. Not exactly a streamlined simple process but EXPress members get ticket discounts that are attractive for business travelers.