I've managed to build an image using beowulf and kernel 4.19, which gives:

Linux devuan 4.19.108-v8+ #1298 SMP PREEMPT Fri Mar 6 18:15:51 GMT 2020 aarch64 GNU/Linux

Used linaro 7.5.0-2019.12 and u-boot v2020.01 plus tweaked arm-sdk settings to get 4 GB.
Getting total memory (with free -b): 3937673216

Available at
http://devuan.metatem.net/dist/raspi4/k … img.xz.sha
(Remove .sha at the end for the actual image. Home server, so be kind...)
Enjoy!

MetaYan on #devuan-arm