There is more good news from Sony. Their recent Bravia range are based on Android TV and they have developed an upgrade that allows those models to support HLG. Alas my Bravia was just a bit too old but I will be able to test HLG on 4K with no HDR for compatibility.
The way I had expected to create HDR content is to shoot in S-Log3 and then use Premiere Pro or DaVinci Resolve to render. S-Log3 comes with a reputation of being difficult to shoot. Particularly with the ambiguity of the advice on how to expose. There is official guidance and then there is the unofficial advice to over expose by two stops. Ollie reports that this is not required on the FS5, when in the correct HLG mode. Some of the YouTube videos show that Ollie is an advocate of setting the camera to the correct mode when you shoot and then not having to rely on a Colorist for a basic grade. HLG makes this easy to achieve.