I can convert any Opencart to iOS app quickly.

For App conversion your website should have following features

1) Responsive Design
2) Should rendered perfectly in all screen size

Your opencart website will looks same in app as you can see in mobile browser.

If you site is not responsive then you check this gig

https://studio.envato.com/explore/mobile-design-development/9710-make-existing-wordpress-site-responsive

For website to Android please check below service

https://studio.envato.com/explore/app-development/10016-website-to-android-app

Portfolio:

IOS: (Opencart to app)

https://itunes.apple.com/us/app/turn2tek/id995023576?ls=1&mt=8

https://itunes.apple.com/us/app/beeexpress/id986755868?mt=8

https://itunes.apple.com/us/app/epago-movil/id1078908157?mt=8

https://itunes.apple.com/nz/app/quran-by-hand-bydy-rsmt-hrwfh/id1088591016?mt=8

https://itunes.apple.com/us/app/ccm-mobile/id1122955591?ls=1&mt=8

https://itunes.apple.com/us/app/blaber/id1095204043?ls=1&mt=8

https://itunes.apple.com/in/app/rafe-lugo/id1094674818?mt=8

https://itunes.apple.com/us/app/truefutbol/id1050975844?mt=8

https://itunes.apple.com/bt/app/hobby-center/id1079278789?mt=8

https://itunes.apple.com/us/app/jaelimseongdo/id1102460444?mt=8