Facing the exact same struggle here. We launched our Shopify upsell/cross-sell app a month ago and are hitting that same initial growth wall against legacy apps with 50+ reviews.
To tackle this, we’ve decided to test a revenue-share model for marketers/partners based on active monthly installations/MRR to incentivize distribution without blowing a budget on paid ads.
Hang in there—getting those first 10–20 active stores to build social proof and reviews is always the hardest part!