Will the ban actually prevent anyone using a Huawei device from accessing a Google service (eg. Gmail) or just prevent them from downloading the official Google apps to do so? I suspect the latter as the first would seem impossible to police. In which case there are better alternatives out there.
The ban might actually provide a bit of a boost to other software developers, if it prompts users to look beyond the Google offerings that came with their phone and seek out some alternatives. In most cases, the alternatives are far better.
For email, try AquaMail. Easily handles my many email addresses split across Gmail, own domains using Google's mailservers, Yandex and own domains using Yandex's mailservers.
OSMAnd+ provides as good mapping as Google Maps (better in remote and off-road areas), is much more customiseable and you can download entire country maps to your phone, without pissing about with Google Maps's silly area selection download. And its navigation is pretty decent, lthough it lacks the Googley stuff like weather and nearest junk food shop listings.
Wire is an encrypted messaging/video-calling/VOIP app, offering everything Hangouts (or whatever Google's offering is called this week) does.
Yandex browser or Kiwi browser are Chrome but with added support for extensions
PulseSMS is text messaging with built in backup and the ability to send and receive SMS through your phone from your laptop.