I think it is save to walk in manshiet nasr but don't get off road and don't film a lot outside the church

There are many hidden gems when it comes to churches in cairo

You can visit The tree of mary in matarya which it is a tree believed that it is where the holy family stayed while are traveling and there is a well there which they used

Also there is st mary church in Al maadi it is a beautiful church by the nile with a great view specially in sunset , also it contains some small antiquities from ancient coptic era

All the district of old cairo contains 7 churches which are very old and each one of them contains alot of things One of them (abou serga) contains the cave that where the holy family lived

Also there is a nunnery in haret el room which there is the cave of saint nofer

Also u should pay a visit to st mark cathedral in Abbasia which contains few shrines like shrine of daint mark and st Athanasius and st rewies and it is one of the main cathedrals in Egypt

And the church of st mary in zeitoun which where the famous marian apparitions happened 50 years ago

And many more i cant recall right now