> If you’ve built your app around their vendor specific stuff like Cloudflare functions, that can be bad news.

There's nothing that "special" about Cloudflare Workers, its mostly "just" a WinterCG runtime. Where you'd encounter problems is if you used the provided interfaces for other adjacent Cloudflare products, like R2, D1, KV, Queues, ect. So what you do is commit a hour of engineering time to make wrapper functions for these APIs. If you're feeling extra spicy, commit another hour of engineering time to make parallel implementations for another service provider. If you allow your tech stack to become deeply intertwined with a 3rd party service provider, thats on you.