As a part of QGIS.ORG grant in 2017, we successfully developed support for visualising 3D in QGIS 3.0.

We have run a successful crowdfunding campaign to implement more features in QGIS 3D. These features should be arriving in QGIS 3.2 - see the crowdfunding page for more details about what is planned.

If there are any features that you are still missing in QGIS 3D, feel free to contact us!