how about a slightly different approach?

partition your sdcard as one btrfs (I am just irritated by the mmcblk1p1, if btrfs I would expect mmcblk1) and add subvolumes user, home and android - set the default volume to user and use the part about android userdata (.service or .mount) of my approach for android on sdcard.

Please keep in mind that I do not have a device atm! So there might be some flaws in the part below.

write your own .service or .mount to mount subvolume home to /home/nemo after /home got mounted but before aliendalvik and your df output should get cleaned up a bit (especially not fusing stuff in circles) meaning the last entries - this still breaks with the-vault as the first sdcard partition visible to it would be mounted to /home/nemo and you would copy .vault to backup.tar in the same directory.

after tmpfs you should have then
/dev/mmcblk1 mounted to /home/nemo
/dev/mmcblk1 mounted to /media/sdcard/($UUID)
/dev/mmcblk1 mounted to /data/media
/dev/fuse mounted to /home/nemo/android_storage

You fuse the android storage a second time to your sdcard? That does not copy anything, you need to mount something to /data/media before it gets fused by aliendalvik... I try to kept the system alone to have everything still working even if the µSD is missing.