Hi, I develop the app "Allkun MON for ISO8583" and published on the splunkbase some weeks ago. Now I'm doing development validations for an upgrade. I ran a scan with the app Python Upgrade Readiness and this report ends with fail (not compatible with python3) but the application don't use python script and has no bin folder.
If your app has no python code in it, I don't see why you should be trying to run the Python Upgrade Readiness against it, as it has nothing to check.
A "fail" makes sense in the context that the check failed, but not that you app has failed to work with Python 3. I cannot see any reason why your app wouldn't work with Python 3, because it has no Python to begin with.
If you want to be sure, I would just run and test your app on the latest Splunk 8.2 version.
Yes, once you upload it to Splunkbase it will run through AppInspect, however you do not need to pass to get on Splunkbase! I have a published app which cannot pass AppInspect for example. A human will review your app just to check it doesn't have malware etc.