The following may be relevant.
The standard text of Acts 18:24-25 reads
However Codex Bezae readsNow a Jew named Apollos, a native of Alexandria, came to Ephesus. He was an eloquent man, competent in the Scriptures. 25 He had been instructed in the way of the Lord. And being fervent in spirit,[a] he spoke and taught accurately the things concerning Jesus, though he knew only the baptism of John.
The reading in his own country (i.e. in Alexandria) is unlikely to be original but it agrees with Codex Gigas (with a change in word order) and is likely to be the original reading of the Western text of Acts going back to say the 3rd quarter of the 2nd century CE. Since the arrival of Apollos in Ephesus according to Acts occurs in 55 CE at the latest and probably several years earlier, the claim that Apollos (or Apollonius) had previously been instructed in Christianity in Alexandria implies that Christianity had been established there before the reign of Nero (probably during the reign of Claudius).Now a certain Jew named Apollonius, an Alexandrian by race, a learned man, came to Ephesus; and he was mighty in the scriptures. He had been instructed in his own country in the word of the Lord; and being fervent in spirit, he spake and taught carefully the things concerning Jesus, knowing only the baptism of John
(I am not assuming the historicity of Acts here, I am discussing what the Western reading of Acts implies about the beliefs of the creator or creators of the Western text type.)
If there was such an early belief in the pre-Neronian evangelization of Alexandria it may provide a basis for evaluating later more developed traditions.