Having the same issue. Many terrabytes of free space, perms look to be in order, but I'm not sure on specifics of what the perms should look like. assets folder is owned by my username, pgdata folder is owned by 103:106. pgdata folder gets created but it's completely empty. Error I get is identical, failing at boostrap script:
2024-04-25 12:46:21.226 PDT [43] LOG: could not link file "pg_wal/xlogtemp.43" to "pg_wal/000000010000000000000001": Function not implemented
2024-04-25 12:46:21.230 PDT [43] FATAL: could not open file "pg_wal/000000010000000000000001": No such file or directory
child process exited with exit code 1
initdb: removing contents of data directory "/var/openproject/pgdata"
-----> Setting PGVERSION=13 PGBIN=/usr/lib/postgresql/13/bin PGCONF_FILE=/etc/postgresql/13/main/postgresql.conf
-----> Starting the all-in-one OpenProject setup at /app/docker/prod/supervisord...
-----> Database cluster not found. Creating a new one in /var/openproject/pgdata...
The files belonging to this database system will be owned by user "postgres".
This user must also own the server process.
The database cluster will be initialized with locale "C.UTF-8".
The default text search configuration will be set to "english".
Data page checksums are disabled.
fixing permissions on existing directory /var/openproject/pgdata ... ok
creating subdirectories ... ok
selecting dynamic shared memory implementation ... posix
selecting default max_connections ... 100
selecting default shared_buffers ... 128MB
selecting default time zone ... America/Los_Angeles
creating configuration files ... ok
running bootstrap script ...
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Not sure where to look if you need further logs