If proof free speculations are your thing…
Funnily enough I’ve given enough examples and sources already in this thread. I think it’s better than “I know someone who knows” and “it’s expert vetted research”. I’ll stick to my theory about Sanskrit/Prakrit diglossia for now.
In the end we are two lay people arguing about a topic we’re not experts in and speculating how things would have been few millennia ago. It’s fine to have diverse perspectives! I’m not sure which quacks you deal with but I wish you all the best.
आ नो भद्राः क्रतवो यन्तु विश्वतः