[nickr]

Seemed to have at least half solved it for Libreelec.

1. Install flix2kodi (see post 1) and chromium (libreelec addons)

2. In chromium settings install widevine support.

3. Launch chromium and navigate to netflix.com (yes a keyboard and mouse helps for this part), log in with your regular netflix account details and keep the box ticked to save the password on this device.

4. In flix2kodi settings choose chromelauncher (not chromium) as your browser. Also, of course, enter your netflix auth details.

At that point I can play, but cannot use my remote to navigate - that's part two I guess.