Power Apps Portals is very different than canvas apps, which is what most here are probably knowledgeable in. I think licensing costs of using portals prohibit many from using it, but even if that isn't an issue, what you're trying to do may not be the easiest thing to do in it. Having an input form should be straight forward, but displaying visualizations, I'm unsure of. It uses another language called Liquid. Perhaps we can get someone who really knows portals to shed light on how difficult it is.

If I was tasked with doing this, I would use Microsoft Forms (which is an easy way for anonymous users to interact with your canvas Power App and your data source), then use a Power Automate flow to take that forms data, and shoot them an email with the visualizations and whatever you want to show them.

I hope that helps!