Research Affiliate Valentin Weber has co-authored a paper, "Shedding Light on Mobile App Store Censorship". The paper studies the availability of apps and app stores across countries.
The research finds that users in specific countries do not have access to popular app stores due to local laws, financial reasons, or because countries are on a sanctions list that prohibit foreign businesses to operate within its jurisdiction. The paper presents a novel methodology for querying the public search engines and APIs of major app stores (Google Play Store, Apple App Store, Tencent MyApp Store) that is cross-verified by network measurements. This allows the researchers to investigate which apps are available in which country. The paper primarily focused on the availability of VPN apps in Russia and China, and the results show that despite both countries having restrictive VPN laws, there are still many VPN apps available in Russia and only a handful in China.
In addition, they have included findings of a global search for the availability of privacy-enhancing and other apps that are known to be censored. They observe that it is difficult to find out which apps have been removed or are unavailable on the examined app stores. The authors urge all app store providers to introduce app store transparency reports, which would include when apps were removed and for what reasons.