The law [1] does not work as an magic all encompassing "ban". It says operating and distributing the app is is unlawful, and the consequence is a huge fine and the enforcement mechanism is suit from the US AG. Nothing says that a sale after doing something unlawful is illegal.

The bigger issue is that the Trump directed the AG not to enforce the law. So something is plainly illegal but is de-facto legal because of executive pronouncement. That is extremely worrying because one aspect of totalitarianism is that the dicta of the ruler has effect of law.

[1] https://www.congress.gov/bill/118th-congress/house-bill/815/...