Quick heads up:
Google finally released Chrome for 64bit ARM and it's now available in our addon repo.
It should also support widevine (usually it's installed via chrome's component updates) so Netflix etc should work with it, too.
If you update Chromium (use the update function of the Flatpak addon) you should also be able to get widevine working.
I haven't been able to verify that myself (as I'm currently away from home), but in the past widevine was installed when you first visited a (streaming-) site that required DRM and then you needed to restart Chrome/Chromium to actually get it working - so try that, too, if it doesn't work at first try.
so long,
Hias