Need some advice on how to do market validation

How did you come up with idea? Thats the message you need to spread around: "Ive noticed that when do X the result is Y, and I have a possibility to make it Z. Do you think this problem with X could use a new approach?".

Talk to 20+ potential customers before building anything, and create a simple landing page to test if people will actually sign up/pay.

So I don't know anything about selling to healthcare orgs, but from what I've heard, I imagine cold outreach could be pretty hard. Which is fine--in some spaces, cold email and the like just don't work as well. Of course, if I'm wrong, and this is a space where you would expect cold outreach to yield much better results, it could just mean your product isn't solving a real problem for healthcare clinics. In any case, it seems like you already have some friends who either are your target customer or could introduce you to your target customer. Are they willing to pay for this platform? Or if they don't make procurement decisions, are they excited enough about this to introduce you to their boss or colleagues who do make those decisions? If so, leveraging your network for warm intros seems a lot easier if you're in a space where cold outreach is hard. If not, I'd want to figure that out (e.g., Is the problem you're trying to address just not one people are willing to pay to solve? Does your platform not solve the problem as well as you initially thought? Etc.)

Build Pad io

To validate your app, focus on reaching out to clinic managers and use your connections or LinkedIn for some intros and visiting local clinics in person might work better than just sending emails.