[Q] Add EXT4 support to ROM to mount external hard drive - Android Q&A, Help & Troubleshooting

Hey folks.
So, I have installed a custom rom to an android box, it runs on EXT4 itself for the system but if I try to connect an external hard drive formatted as EXT4 it only says it's unsupported and will give me the option to format it, which I won't do. I don't want FAT32 or ExFAT or NTFS. I need EXT4 for reasons.
I was using this hard drive with my RaspberryPi before and it worked fine. Also this box is rooted and I can mount it manually with "mount -t ext4 /dev/block/sda /mnt/hd" or whatever and I can see the files, have read/write BUT other apps can't see it due to Android security (even messing with chown/chmod).
I'm not sure how to add EXT4 support to mountable storage at all to a ROM. The dev seems to be busy with other projects and won't help, so I have to figure it out on my own.
I have searched left and right but couldn't find any answer on how to do it myself, nothing very conclusive.
Should I just add the hdd to fstab.amlogic? Does it have anything to do with vold? I wanted the system to be able to recognize it and mount it, not mount it myself like this.
Futher info:
This is the BLKID for the hdd:
Code:
/dev/block/sda: UUID="4de...d5" TYPE="ext4"
/dev/block/vold/disk:8,0: UUID="4de...d5" TYPE="ext4"
This is the fstab.amlogic:
Code:
# Android fstab file.
#<src> <mnt_point> <type> <mnt_flags and options> <fs_mgr_flags>
# The filesystem that contains the filesystem checker binary (typically /system) cannot
# specify MF_CHECK, and must come before any filesystems that do specify MF_CHECK
/dev/block/misc /misc emmc defaults defaults
/dev/block/system /system ext4 ro wait
/dev/block/data /data ext4 noatime,nosuid,nodev,nodelalloc,nomblk_io_submit,errors=panic wait,check,encryptable=footer
/dev/block/cache /cache ext4 noatime,nosuid,nodev,nodelalloc,nomblk_io_submit,errors=panic wait,check
/devices/*.sd/mmc_host/sd* auto auto defaults voldmanaged=sdcard1:auto,noemulatedsd
/devices/*dwc3/xhci-hcd.0.auto/usb?/*/host*/target*/block/sd* auto auto defaults voldmanaged=udisk:auto
/devices/*dwc3/xhci-hcd.0.auto/usb?/*/host*/target*/block/sr* auto auto defaults voldmanaged=sr0:auto
/dev/block/loop auto loop defaults voldmanaged=loop:auto
# Add for zram. zramsize can be in numeric (byte) , in percent
/dev/block/zram0 /swap_zram0 swap defaults wait,zramsize=524288000
/dev/block/tee /tee ext4 noatime,nosuid,nodev,nodelalloc,nomblk_io_submit,errors=panic wait,check
Thank you.