I think the answer here is to stop passing "console=ttyS0". This is
something that is typically only done for debugging.

dmesg shows a 14 second delay between the "console [tty1] enabled" and
"console [ttyS0] enabled" messages. I suspect that because console=ttyS0
is passed the kernel is going to dump all the messages accumulated in
dmesg so far to the serial port when it is registered as a console
device. Because this is a slow device this consumes significant time,
and it happens in an initcall so it blocks boot progress. Then boot from
that point on is slowed down by printing messages out on the serial port
every time something is printed to the kernel log.

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  pc: no message on the screen for ~30s on fast HW

Status in linux package in Ubuntu:
Status in snapd package in Ubuntu:

Bug description:
  The boot on real HW (ARock B450, Ryzen, NVME 240Gb) takes a long time
  without any visible feedback.

  Video: https://photos.app.goo.gl/RmaLviXNorjeh5BP7
  With grub debug: https://photos.app.goo.gl/PJuXdxp8uedr7fWp9
  (google photos has degraded quality quite a bit, may upload the originals if 
too bad)

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