I’ve never jailbroken my phone and AltStore works great. It’s a tool for sideloading apps and you can download .ipa files with it. Delta is available in the app. The only thing is you need a computer. Here’s the link if you wanna try it out: https://altstore.io
Try to Download AltStore, then you aren't subject to Revokes https://altstore.io/ Just install alt server then plug your iphone into a pc, after this you will be able to download some of the developers apps, such as Delta (which is a really good emulator for multiple systems), and any app provided you find the iap file for it online, unfortunately you can only have two things installed at once using Altstore