pg_upgradecluster version 10 to 16 question

[Jim Cunning]

I had a Ubuntu 20.04 LTS system with a postgresql version 10 database, and the system became unbootable.  The database was stored in /var/lib/postgresql/10/main and I was able to recover the entire contents of the data in that directory and below.  I now have a system running ubuntu 24.04 LTS with postgresql version 16.

I obviously no longer have a running version 10 server, so I cannot use pg_dump to retrieve the data.  I have placed the recovered version files in /var/lib/postgresql/10/main on my new system, alongside the /var/lib/postgresql/16/main that was created when I installed postgresql.  I have tried several iterations of the pg_upgradecluster command, a Python script provided by Ubuntu, but it says it cannot find the database files.

I also see from the postgresql wiki pages that there is a pg_upgrade utility program, but cannot find in any of the Ubuntu-provided installation files.  Can anyone provide some guidance on how I might proceed?

Thanks in advance.