I mentioned this early. Really do no see the point in running old OS stuff in a sandbox and the code a ccompletley new OS to run the sandbox in.
We have already got a brillaint sandbox its called UAE, run it on any system you want (more or less). There are even linux installs around that are so small and with running UAE in mind, so you would not even not notice xit wasnt native OS3.9.
We already have MorphOS and OS4. They are the most modern an amiga like OS is going to get.