Ask HN: How to solve the customer onboarding bottleneck?

We sell a B2B SaaS to a nontechnical market. In the early days, we had the privilege of working with each new customer in weekly calls, doing a thoughtful onboarding in which we carefully migrated their data into our architecture and thought hard about their problem. Suddenly, our sales team started crushing it and we have nowhere near that level of capacity to support onboarding. At the same time, our customer lacks the technical abilities to onboard themselves, which has created a severe bottleneck with onboarding.

Has anyone else gone through this struggle. How did your Product/Success/Support teams address this "onboarding bottleneck" issue?