Some popular tools are missing in GIMP 2.10 in Ubuntu 20.04

It is certainly there in Gimp 2.10.22 (which I installed from ppa:ubuntuhandbook1/gimp), maybe it does not show up because the toolbars are grouped by default.

Go to Edit -> Preferences -> Interface -> Toolbox and uncheck Use tool groups.

Before and After

Note: The other answer is about Heal selection tool, which OP originally wanted to enable.