I had a DJI Ronin gimbal delivered today

. And a good fluid tripod head.

. Got an HDMI to Thunderbolt 3 converter to allow recording directly into a laptop.
The purpose is exactly the same as your thoughts - get into videography but something a little more that the usual PoV/YouTube running-gun piece to camera. My eldest and I have a number of cameras but currently only my Hero 8 is true 4k. The intention is to cut our teeth on 1080p but recording 1080i from a number of mid to higher range but older cameras - Nikon D5100, Sony A6000 and Canon EOS5Diii. I have a bag full of L glass but only a couple of primes. The cameras we have also have limited internal recording quality, but, using the HDMI output we can get 4:2:2 at 10 bit compared to 4:2:0 at 8 bit. That gives access to a great deal more data at the editing stage.
Our intention is to mimic that cinematic approach using good lenses with wide (or managed apertures) to give that depth of field that is impossible using mobile phones and fixed aperture cameras.
Having done photography for many years, some of the skills are transferable. That said, the additional skills needed are huge - the whole workflow has to be managed. Using manual focus (Except for the Sony) means you have complete control over DoF but your shots are limited to fixed or semi fixed - they have to be planned and executed. The Ronin is a fabulous bit of kit but still you ned to manage your shooting carefully. It does however give you a very stable platform. I'll be playing with it for days yet.
Just getting the footage captured in the camera is just the start of the process. Am well used to colour and exposure management as well as some creative changes to the colours, but, as you say, video technology allows you to apply look and feel to an image that would have been impossible using filtration and lighting. Editing and colouration is another set of skills to master.
You see a lot of people talking about shooting in 8k or 6k to subsample down to 4k or using 4k down to 1080p. That gives some flexibility to manage composition in the computer after shooting. Would love to do that having done that in stills for a long time, but, being forced to do that in camera also makes you think about the whole sequence before you press the start-record button.
Some things like cranes and dollys will no doubt come in at some stage. Probably first will be a slider to allow some horizontal camera movement with greater control of subject distance and Dof control. The gimbal seems to a little to granular to control that kind of scene - but I've only had it for a few hours. It does however, have facilities for doing panoramas and time-lapse shots - excellent features for both stills and videos. Going to be giving those a try. In conjunction with the time-lapse features on the Hero 8 I hope to get some awesome video.
Of course - you also need a story to tell. A whole new creative aspect that we have to discover and learn. Like you said, some form of style and genre needed to help the direction of travel, to keep some sense of purpose.
Documentaries? History? PoV? How-tos? Story telling? Who knows?
I see many months trial and error and discovery ahead. We now have a challenge. Can't wait.