I believe F-Droid is doing quite ok. So is the Galaxy Store. On iOS, Apple created a very complicated process which is region and even country-specific. Hopefully this will change once the EU, the US, Japan and everyone else currently suing Apple is done with them. But I do share the sentiment from the article - I wish it wasn't necessary to escalate such matters to the level of regulation
At least on iOS Apple has just been fined 500 million - as a start - because the way they implemented third-party app stores was so blatantly against the DMA. I think we simply don't yet know how users and corporations will react to it.