Ah yeah, about the vbmeta --disable-verification.
It seems there is a bug in aboot, we can only hope it gets fixed in an update.
aboot just crashes, when verification is disabled:
[1580] battery_voltage: 4241918
[1820] MultiSlot true, partition name boot_b
[1830] AVB version 2
[1830] avb_slot_verify.c[1830] :[1830] 417[1830] : DEBUG: [1830] Loading vbmeta struct from partition '[1840] vbmeta_b[1840] '.
[1840] avb_vbmeta_image.c[1840] :[1840] 226[1840] : ERROR: [1850] Hash does not match!
[1850] avb_slot_verify.c[1850] :[1850] 539[1850] : ERROR: [1850] vbmeta_b[1850] : Error verifying vbmeta image: [1860] HASH_MISMATCH[1860]
[1860] ReadRollbackIndex Location 0, RollbackIndex 0
[1860] avb_slot_verify.c[1870] :[1870] 699[1870] : DEBUG: [1870] vbmeta_b[1870] : VERIFICATION_DISABLED bit is set.
[1870] avb_slot_verify.c[1880] :[1880] 308[1880] : DEBUG: [1880] boot_b[1880] : Loading entire partition.
[1880] read from boot_b, 0x4000000 bytes at Offset 0x0, partition size 560070656
[1890] data abort, halting
[1890] r0 0x91400000 r1 0x04000000 r2 0x9385339c r3 0x04000000
[1890] r4 0x04000000 r5 0x8f85339c r6 0x8f62b378 r7 0x00000200
[1890] r8 0x21620000 r9 0x00000000 r10 0x8f854e64 r11 0x8f8533a8
[1890] r12 0x8f8369ac usp 0x00000000 ulr 0x00000000 pc 0x8f632b18
[1890] spsr 0x80000153
[1890] fiq r13 0x8f81d000 r14 0x00000000
[1890] irq r13 0x8f82228c r14 0x8f611ef8
[1890] *svc r13 0x8f853220 r14 0x8f60f780
[1890] und r13 0x8f81d000 r14 0x00000000
[1890] sys r13 0x00000000 r14 0x00000000
[1890] bottom of stack at 0x8f853220:
0x8f853220: 00000000 00000200 04000000 8f8369ac |.............i..|
0x8f853230: 8f8533a8 145d1c00 04000000 21620000 |..............b.|
0x8f853240: 00000000 00000200 00000000 8f8369ac |.............i..|
0x8f853250: 04000000 8f85339c 8f8533a8 8f62b378 |............x.b.|
0x8f853260: 00000000 00000000 21620000 00000000 |..........b.....|
0x8f853270: 00000000 04000000 8f876dc0 00000200 |.........m......|
0x8f853280: 00000000 00000000 00000200 00000000 |................|
0x8f853290: 00000000 00000000 21620000 00000000 |..........b.....|
[1890] HALT: reboot into dload mode...