Scenes that are available in the gallery but are not in-game currently will eventually be in-game once their corresponding stages/events/enemies are completed. Gallery-only scenes are temporarily such -- they've simply been completed before their corresponding gameplay elements. In short, yeah, expect gameplay to evolve substantially.
We typically go over topics for what we're working on beyond what makes it into the releases in our monthly progress updates on SubcribeStar and Fansly. Examples of that this month is how we're looking at equipment slot breakdowns for the potential additional playable characters, as well as showcasing some work done on new Red-Light Streets maps. Past examples include Onyx's expanded move set and unlockable skills, mission types and layout designs, etc. In the future I'd like to provide access to these to itch supporters.
Regarding priorities, it's a balancing act of showing meaningful progress each month, progressing toward larger goals, and simply keeping the team's plates full, even if it means working on something that won't be seen for a while.