Is a Native App or Web App best for my circumstasnce?

I am looking for some advice! I am currently working on a project for a company. They focus on feedback for businesses. I built them their current system native on iPad. They use iPads to gather data for businesses. It has been a real pain servicing and updating these devices and as they scale, they want to make sure they are doing it right!

I have tried MDM providers and it really isn't working. There really isn't a good way to fix things and it would be perfect if we could literally take control of the device OTA. I know this isn't really possible. So, we are considering moving over from a native iOS app to a Web App so it can be used by any device and there isn't really a worry about updating the app because it's just a website.

I have been told looking down the road it would be good to use Ubuntu Core paired with something like a Raspberry-Pi to display the website if we went that route. For the time being we would continue to use the iPad's but just show the website instead of native app.

I am looking for any advice you can give to help us make this decision. Thank you so much in advance!!!