If there was a Linux Apple App Store, I would buy stuff from it. I already buy from Steam. OSS doesn't have the answer to everything. Boutique software has value that people are willing to pay for.

Linux applications are being sold. In fact, GPL-licensed applications get sold, so it's not even the OSS part that's holding you back. ElementaryOS even has its optionally-paid app store: https://appcenter.elementary.io/ Autodesk and other industrial software providers are quite happy to sell you software, though unfortunately not through a unified app store.

In practice, I expect a paid Linux app store to go down about as well as the Microsoft Store has. Especially now, in the age of vibecoding.

flathub.org ?