The problem here lies with Pakistan, not Apple and Google.
An alternate App Store operating in Pakistan would be subject to the same unjust laws as them. The most Apple and Google can do is leave the market. There's an argument for that, but that doesn't make those apps available in Pakistan, and, more importantly, doesn't end the oppression of Ahmadiyya Muslims in Pakistan.
There are arguments against gatekeeping tech companies, but this isn't one of them.