The whole legal situation around AI models isn't clear and common Open Source licenses are an ill fit for them because you aren't distributing the source, but just a binary blob. You can't just take any random accumulation of data and slap a Open Source license on it, especially when that accumulation is the result of proprietary data, incompatible licenses and all that.

Most people don't care and just remix everything as they please, but just because you can download for free something doesn't make it Open Source. Furthermore a lot of the models exclude commercial use or otherwise restrict the use in ways that are incompatible with the Open Source definition.

Has any of the model made it into Debian yet?

What do you define as "source" for an AI model? Training code? Training data set?