I am not really familiar with the process of making a model so take this with a grain of salt.
TLDR; if you think you will enjoy streaming more with a paid model and feel confident in your ability to entertain others then you should do that, otherwise it might be better to make your own.
Is that something someone would watch?
I believe that you're thinking too much about the model. While it does play a big role, a bigger part of getting viewers is to be entertaining. A model can attract viewers but it does not guarantee that they will stay, and seeing as models can get quite expensive I would advise against paying for one since if you're not entertaining to the viewers then soon there will be no one to actually see the model.
HOWEVER, if you do not really care about numbers or viewers and are just doing this for fun and you believe you will enjoy yourself more with a paid model (and can afford it) then go for it! If you think you'll have more fun creating your own model then do that. IMO the best approach to streaming is to just enjoy yourself since if you yourself are not having fun then the viewers likely won't either. Not to mention only focusing on numbers can be quite stressful and de-motivating so I really believe your top priority should be to just have fun.
Let me re-iterate that I am just a single viewer out of thousands in a stream so I would probably go ask more people about what they think (i.e in Discord servers or other forums) before making my decision.