Paragon (YC W20) raises $13M Series A to build Plaid for SaaS

I would love to learn more about the embedded integrations market "by the numbers", any good references or links out there? I'm curious what the average integrations portfolio looks like for a small, medium, enterprise business. Are integrations a recurring aspect of most business or do they tend to plateau based on domain (e.g. n common integrations for the insurance/trucking/... market, once a business hits them all no more integrations)?