Finally - after some 6 hours of work, and multiple new drivers, fixes to the tree - #uboot with internal storage (ufs), and USB gadget is up on the CMF Phone 1 (MediaTek MT6878). This was my first attempt at writing some uboot drivers - a learning experience. But I'm glad it all worked out, and now #postmarketOS will have an open bootchain on a modern MediaTek platform! Looking to upstream these patches after I clean everything up.