Based on the profile tab, we are hanging on the beforeRender function

I see, this would mean it is hanging somewhere in you custom script, try to investigate there.

Is the "full" or the regular version suggested?

The full is bigger because it has installed also additional extensions and some OS fonts.
The full is based on Ubuntu and the default is based on Alpine.
There is no general recommendation, but if you care about the image size, you will use the default.

As for the export, this site says I do not have sufficient permissions

Please upload to some onedrive, dropbox... when you need to share something here. The forum for some reason doesn't accept uploads sometimes.