I have quite a bit of work to rush tonight, going to do a quick post to share what I been research recently. I have a Learning Management System project recently, and I have chosen to build in on LearnDash after doing some research. I build a demo and show it to the client, and I manage to get the project.
Once the project kickstart, one of the new requirement that bugs me is the client wants a mobile app that working with LearnDash. Below are what I research; the choices seem like pretty limited.

Apppresser

Build Mobile Apps with WordPress | AppPresser
The #1 way to convert your WordPress website into an iOS and Android mobile app. Build in WordPress, deploy to the app stores. Easy and affordable.

Apppresser is the primary services I plan to rely on to build the mobile app for LearnDash site, it seems like having integration with LearnDash by default, the pricing is still acceptable range, but so far the initial testing is a mess.

Wisdmlabs

LearnDash Mobile App Development for iOS and Andorid
Unleash the power of mobile learning with an exclusive, white-labeled app for your LearnDash Website. Offer a wholesome learning experience with WisdmApp.

This company seems like having an in-house solution to integrate the Mobile app with LearnDash, but you need to request a quote, and they build for you. Not a SAAS solution that I want.

BuddyBoss LearnDash

Mobile App for LearnDash • BuddyBoss
Launch your own WordPress and LearnDash powered native mobile learning app. Try it, and manage your courses from your LearnDash mobile app.

It pretty much covers everything if you check on the landing page. It has features showing videos, and you can try the demo. The price is a bit on the high side, but if it can deliver what it claims, it seems like pretty reasonable compare to other solutions.

Tangible

Mobile App for LearnDash - Tangible
It’s time to take your relationship with your students to the next level Be with them everywhere and become an essential part of their day to day. Get started now Don’t kid yourself You are not your students’ priority. You’re probably not even in the top 10 most important things…

From the demo looks like a pretty polished product but with it has a high pricing entry point.