Distributing In-House Apps

You are getting really deep into Application development with this question. Which is a bit out of band for what is usually discussed on this forum and most of us are not greatly familiar with.

Does the application work when you use TestFlight? There may honestly be something wrong with the application itself. 

Your easiest solution would likely be something like Single App Mode to Chrome and Register the Chrome browser for management with googles admin console. Then limit the Chrome browser to a single website. Or to use a tool like Jamf Safe Internet to limit website access to the single site you want to allow.

You need to upload the archived .ipa file into your MDM and also provide a provisioning profile. Some of the documentation from Apple can be found at this link.

https://support.apple.com/guide/deployment/distribute-proprietary-in-house-apps-depce7cefc4d/web

Hi @ChrisTech 

I've used KioskPro https://www.kioskgroup.com/pages/kiosk-pro-software (And of course via App Store and Apple School/Business Manager) for the purpose you have. 

I'm fairly sure there are some other posts on here mentioning it.  I have the free version in a few locations and a paid one for another location where we needed a few more features.  The documentation is fairly straight forward.  I use Jamf to deploy a Configuration Profile to put the device in Single App mode with the app being Kiosk Pro

Thanks for the link, I check it.