Automatic partition resize after installation OR device-specific build size instructions

I've just found out that Automatic System Upgrade can now read an UCI OWUT config parameter that tells it to expand the filesystem to the given size:

$ uci set attendedsysupgrade.owut=owut
$ uci set attendedsysupgrade.owut.rootfs_size=1024
$ uci commit

Problem is that the parameter has a max. of 1024 (1 GiB). This should be increased. I have reported it to the ASU team here.