You're right that normal dead man's switches create unnecessary notifications. By definition, every check-in you acknowledge is unnecessary. Only the last one, when you're actually dead, is necessary.
So you invert it: from push-based to pull-based. This creates a different set of issues. Now your partner or contacts must keep the app installed and set up over the years. They will change phones, life will happen. But if they don't properly custody their keys, they won't be able to access the data when they need it most.
There's an argument for both approaches, and neither is necessarily superior. When we built our dead man's switch, we were thinking of sending a last message to non-technical people who aren't good at long-term key custody. But if your recipients are more technical or you expect this to be needed in a short timeframe, this approach reduces notifications, which is a plus.
By the way, kudos for your cryptographic choices and for making the app code source-available. The next step would be reproducible builds with instructions for manual builds from source. Otherwise, I can't be sure that what I'm installing matches the published codebase, which diminishes the value of sharing the code.
What I'm curious about: how is this different from Bitwarden's Emergency Access? You can upload attachments to your vault and set different emergency contacts for different vaults. So if you're already using Bitwarden as your password manager, why not use its Emergency Access feature too?