Commenting on this a bit late, but in case anyone reads this later too:

UUIDv7 support unfortunately didn't make it to Postgres 17, since the RFC wasn't completely finalized yet by the time of feature freeze (April 8), see discussion on pgsql-hackers:

https://www.postgresql.org/message-id/flat/ZhzFQxU0t0xk9mA_%...

So I guess we'll unfortunately have to rely on extensions or client-side generation for the time being, until Postgres 18.