How many Sites with Custom Domains i can publish through Netlify

Hello dear Netlify Members and Support,

i’m planing to build a SaaS Plattform like Shopify. part of my business will be that the customer can have their own domain on which their shop runs. I’ve solved everything on aws so far, but I’m now coming up against a limit (number of S3 buckets and the domain assignment). My principle when creating my platform was always that it scales from 1 to 10000 without resorting to servers or manually switching anything later in production.
I have now become aware of netlify. I would like to host the static sites with Netlify and my images via S3 (I don’t need custom domains for that).
So far I haven’t come across any limitations that make my project impossible (except for bandwidth, I can definitely upgrade my account if it comes to that).
But I still wonder if it is possible e.g. Hosting 500-100 sites with the associated custom domains via a simple Netlify account, or is there a limit that I haven’t found yet?
I thank you for every answer and apologize for my bad English.

Here are some soft limits which can be upgraded after contacting support:

  1. 500 sites per account
  2. 10 domains purchased through Netlify - unlimited externally purchased domains can be used

There’s a hard limit of 100 domains per site (primary domain + domain alias included) and this cannot be changed. However, on pro and above plans, you can opt for wildcard domains.