rootless container permission error

Creating a container with "user:1000:1000" in the compose file generates these errors:

chmod: /var/lib/postgresql/data: Operation not permitted
chmod: /var/run/postgresql: Operation not permitted
The files belonging to this database system will be owned by user "myrootlessuser".
This user must also own the server process.

...

fixing permissions on existing directory /var/lib/postgresql/data ... initdb: error: could not change permission of directory "/var/lib/postgresql/data": Operation not permitted

This seems to happen because i'm using a subuid (which the volume correctly chowns to the bind path)

A solution to this could be to let us set the postgres user UID and GID manually, as suggested in https://github.com/docker-library/postgres/issues/1068

This works without using subuids, but doesn't if so:

services:
  pgdbex:
    image: postgres:16-alpine
    cap_drop:
      - ALL
    user: 1000:1000
    environment:
      POSTGRES_USER: 
      POSTGRES_PASSWORD: 
      POSTGRES_DB: 
    volumes:
      - ./db:/var/lib/postgresql/data 

This doesn't work in either case:

services:
  pgdbex:
    image: postgres:16-alpine
    cap_drop:
      - ALL
    user: 1000:1000
    environment:
      POSTGRES_USER: 
      POSTGRES_PASSWORD: 
      POSTGRES_DB: 
    volumes:
      - pgdbdata:/var/lib/postgresql/data 

volumes:
  pgdbdata:
    driver: local
    driver_opts:
      o: bind
      type: none
      device: ./db

Start by reproducing the failure with the two Compose examples in the issue, comparing bind mounts and the named volume under a rootless user. Then inspect the Postgres image's initialization and permission handling. Done means a rootless container using user 1000:1000 can initialize the database and start successfully without permission errors.