To run it for development and have the latest sourcecode running we need to either copy the lib folder of live-common in cli/nodemodules or use something like yalc. _We used to use yarn link but symlink are not properly working and creating dup issues.
You likely want to run yarn watch in a terminal and do this in another terminal (from top level):
yalc publish # link live-common
cd cli/
yarn
yalc add @ledgerhq/live-common
yarn link # will make ledger-live CLI available
yarn watch # incremental build as well
Assuming that yarn global bin is in your $PATH,
You can run:
ledger-live
and it will always use your latest sourcecode.