Percona Server 5.6 was not compiled for Ubuntu 20.04 but last version you can get PS 5.6 is for Ubuntu 18.04 that you can get from Download Percona Server for MySQL 5.6 .
You can still try compiling yourself for 20.04 but you might find some challenges along the way
Hello @Daljit1,
Your software is extremely old in many ways. The best solution for you is to set up a brand new Ubuntu 22.04, install MySQL 8, and do a logical dump from your old 5.6 and import that into your new 8.0.