For the record: my version of PVE positively ignored the splash time setting for Seabios. It did work for UEFI though.
# pveversion
pve-manager/9.0.3/025864202ebb6109 (running kernel: 6.14.8-2-pve)
Thanks @pulipulichen - actually this *is* what I get. That's what I meant with "boot menu" which ever other BIOS offers for a one-off change of the boot order. Now, that I have time to actually read the screen it even says "boot menu" on the tin...
Thanks @trickyearlobe - I now get a glimpse of the start screen. Still to short though. Applied @fba 's configuration, but it seems to make no difference:
Can't see what's wrong with it:
# head 200.conf
args: -boot menu=on,splash-time=20000 -vnc...
Is there a way to increase the time window for pressing ESC?
Between reset, switch to the noVNC console and pressing ESC I'm just too slow. And I don't feel like doing video game exercise just to get the sequence right in so many millisecsonds.