Amazon could bundle rides with package deliveries and get the pre-existing driver and passenger network from Lyft. Lyft was actually telling drivers to work with Amazon when the pandemic started (1).
Waymo could take Lyft’s aggregated rider demand. They already have a partnership to transfer autonomous rides from Waymo to Lyft during bad weather situations and refer Lyft riders to Waymo vehicles (2).
Edit - links below.
(1) Amazon - https://www.theverge.com/2020/3/27/21197699/lyft-amazon-coro...
(2) Waymo - https://www.fool.com/investing/2019/05/08/waymo-lyft-partner...