I just did a drag and drop on to my Start9 web UI without any issue.
Here's the guide they put out for what its worth. It even has a nice little video.
Discussion
Yeah, I'm happy for you. For me it says invalid package type.
maybe nostr:npub1xv8mzscll8vvy5rsdw7dcqtd2j268a6yupr6gzqh86f2ulhy9kkqmclk3x can help? He's been guiding me through this process.
I left an issue on their github as well.