Thanks @tjcs90 for your efforts! Does the kernel you built contain lvm / device mapper modules?
I tried to boot my fresh Debian 10 installation with it, but it failed to an “Incompatible libdevmapper 1.02.155” error, which might be because I installed my system on top of LVM.
If that’s the case would you mind including LVM / device mapper (dm) support in your next build?