I think you can get most of the benefit by just banning targeted advertising.

Require that every user must be shown the exact same ads (probabilistically). Don't allow any kind of interest or demographic based targeting for paid content.

Advertisers would still be able to place Ads on pages they know there target audience goes, but wouldn't be able to make those same Ads follow that target audience around the internet.

Going too far - laws state that if you were paid for a testimonial by a firm, or if the firm provided the service or product you disclose / it counts as paid endorsements /

You don’t need to go too far down the rabbit hole. You need to introduce friction to ads.

Subscription revenues are tiny when compared ad revenue, so I expect people will resist this idea ferociously.

Paying someone for promoting your product or message. I don’t think it’s all that complicated. Talking about your own product on the internet is fine. Paying to promote your message wouldn’t be. TikTok and Reddit and Instagram aren’t trying to keep people endlessly scrolling because they are free-speech fanatics. It entirely comes down to “more time in app = more revenue”. Take away that monetization method and you take away the single incentive that has driven virtually every dark pattern that has developed in social media in the last two decades.

What counts as pornography? What counts as art? What counts as music? Please, yeah we know, we absolutely know categorization is hard, doesn't mean there is no benefit in having them and shaping them as we go.