Thanks to the documentation and the sources provided by @mntmn, it was easy to get #QMK working on the MNT Reform #mechanicalkeyboard -> https://github.com/qmk/qmk_firmware/pull/15561 OLED display and backlight work like a charm.The original #firmware was great, but I need sticky keys and layers for my workflow.
My port of #QMK for the @mntmn Reform keyboard (standalone) has been merged into the "master" branch, thus it is now possible to use the online QMK Configurator to create custom layouts for this keyboard/firmware https://config.qmk.fm/#/mntre/LAYOUT