You can run stateless DHCPv6, i.e., without handing out prefixes. It's a fairly normal situation that clients choose their own addresses from prefixes handed out via RA, but that they get auxiliary configuration (such as UEFI boot, or DNS servers before RDNSS was a thing) from DHCPv6. You'd probably need to make sure there was an RA on the network hinting about a DHCPv6 server (the “Other” flag), though.