Coreboot (and distributions) have an option to automatically run me_cleaner if you build a build a full image (need to obtain the IFD and other blobs). So, if your motherboard is supported by coreboot you can try to build an image including the neutralised intel ME region.
To flash this image internally (with flashrom) you typically need to unlock the region that contains the Intel firmware, so you can do only after an external flashing (for which there are no restrictions).
If you want to try this I recommend to first build the image containing only the BIOS/coreboot payload and then attempt to run me_cleaner.
Coreboot like all big projects requires its own toolchain and it’s quite annoying to build on NixOS, but it’s possible. If you’re interested I made this thing to build coreboot images using Nix: you just need to write the configuration of your board. I haven’t used it in a while but it’s pinned to a working coreboot version.