Use of LuCI Attended Sysupgrade with an x86 device

I understand the upgrade process with x86 devices is more complicated, I have already configured mine (Protectli vp2420) with 23.05.5, I have expanded the root partition, installed a few packages and performed the initial setup and configuration, everything is working fine.

Looking at a future upgrade, can I safely assume that if I use the Attended Sysupgrade process from the LuCI web interface, everything will be preserved (larger root partition, packages, configuration, etc.)?

Thank you

No to that one, yes to the retention of packages, configuration et cetera.

The LuCI ASU app is mostly designed for simplicity and hence does not have the option to configure the rootfs partition size, so will resize it to 104 MB (the default for x86) when you use it to sysupgrade.

Only one ASU client (owut) exposes that option, and it's only available on SNAPSHOT builds currently.