There is a need to work on particular features of the software as it progresses along and have separate brances for demos.

The software needs to be built in a way that features can be demoed like a feature set library. We have one portal that on a single click show a specific feature working. Navigation between the portal and the individual feature showcase must be seamless.

Develop software as a series of plugins (feature packs. Then load different version of the same feature/plugins and turn off the other version of the same that have already being used.

This way we can always show working features. Look into Unreal Game Feature functionality. See the following https://docs.unrealengine.com/5.0/en-US/game-features-and-modular-gameplay-in-unreal-engine/