How would you build early traction for a B2C app before the MVP exists? I will not promote

I’m a non-technical founder building my first B2C app. Without going too deep into the app, the idea sits around gamifying walking and making it easier/more rewarding for people to engage with nature. I’m commercially focused, so I’m speaking with a potential CTO/technical lead and working through what the MVP needs to look like. It’s still very early - pre-product and no user metrics yet. I’m also on an accelerator at the moment, which has made me think more seriously about what I need to demonstrate to angels/VCs before the product is live. Right now, the only outwards facing asset I have is a very basic landing page where people can input their email (0 sign ups) So my question is: if you were in this position, what would you focus on over the next few weeks to start demonstrating user interest? For example: Build a waitlist and aim for the first 100 sign-ups? Start posting on TikTok/Instagram and build an audience around the problem - if so, what would I post without the product being there? Run small Meta/TikTok ad experiments to test whether people convert to a waitlist? Build a small community first? Focus more on user interviews and evidence of demand rather than vanity metrics? I don’t want to manufacture a big waitlist just so I can put a number on a pitch deck. I’d rather find some early signal that suggests people want this when we launch.