How to design an optimistic/eager multi-step form?

An app that I'm building has a comprehensive onboarding process, involving a multi-step form with 5 steps. It's already a pretty boring process to fill out 5 forms with a bunch of image attachments, and the users also have to wait for each step to submit before moving on to the next. The backend's API is also designed to accept form submissions at each step.

Is there a way to let the user move on to the next step instantly after pressing the "Next" button, without having to wait for the form to be submitted at each step? If I make the submission in the background, I also want to be able to gracefully handle the scenario of when the submission fails. What would be a good UX for this?

One suggestion I found here was to go to the next step immediately and show a loading interface there instead of on the current step, but this only solves part of the problem and still leaves the user waiting for some time before being able to fill up the next form, especially if they are on a flaky connection (which would be the case for many users on the app that I'm building).

Thanks in advance!