Macbook pro 16inches 2019 fails to reinstall catalina on recovery mode after erasing hard drive, and T2 chip dissallows to boot from external drive

This is how I solved the issue.

You need another Apple computer running Catalina.

  1. Make a time machine backup of the working computer.
  2. Boot the non-working computer in recovery mode.
  3. Recover from that backup.
  4. Continue from there...

Hope this helps other people.