I finally found a plugin (vst x64) that serves as my midi player in GP! (Windows version).
It’s a midi editor/sequencer/looper with many functions that can also be used as a simple midi player. It works perfectly on GP, the automation is apparently complete, it is synchronizable (or not) with the play/sop, etc.
This is a plugin that has not been developed since 2012 and there is a Mac version but it must not have worked for a long time. It’s a demo donationware version but can’t be bought anymore because thepiz.org is inaccessible. The only limitation is a “demo” window in the GUI. So it is free and fully functional.
It can be downloaded here:
This is a pack containing in addition 16 other midi utilities