Mobile optimization problems for web apps

Hi everyone, I wanted to ask for your feedback on a problem I'm facing while making my first web app, lofi.co.

I'm currently in the process of ending the open beta (which you can check out at https://testing.lofi.co if you want) as the first version of the app is complete and all bugs have been fixed, but I'm facing a few annoying problems with mobile optimization, in particular on iOS, which are causing a delay with the public launch.

The app is designed to work on desktop, but I've decided to make a decent-looking version of it for mobile since I have a good audience on Instagram and I know a good part of the traffic will come from there. Thing is, my developer is having a problem optimizing some of the features on iOS, mainly regarding volume control and buttons interactions.

My question is: is it better to have a 90% working version on mobile or not having it at all and leaving a landing page explaining how the app only works on desktop? Consider I've put some pop-ups here and there recommending to visit the site from desktop, but I'm still not sure if that will do the job.

Looking forward to hearing from you, it would really help out!