I noticed you are thinking about using a pallet extruder. You can buy one here:https://mahor.xyz/es/producto/pellet-extruder-v3/
In case you want something cheaper, you can try to make something like this yourself;https://www.3ders.org/articles/20141226-new-universal-pellet-extruder-is-an-open-source-pellet-extruder-for-multiple-materials.html
I recommend buying the one from Mahor since that one will work great for sure. You are not going to want to end up using a faulty extruder you made by yourself because the print quality will deteriorate a lot!