How to install SideStore (MacOS)
This is the MacOS tutorial, if you want the Windows one, here:
Connect your iPhone to your computer.
Download AltServer, iCloud (Web, not Microsoft Store) + iTunes(also web, not Microsoft Store), jitterbugpair and SideStore.ipa
Install AltServer, open it, then hold Shift while clicking on it, clicking Sideload .ipa..., clicking your iPhone, selecting SideStore.ipa and then typing in your Apple ID and password.
After it's installed, unzip and open jitterbugpair. It will pop up with a trust dialog on your iPhone, just accept it and run jitterbugpair again.
Transfer the .mobiledevicepairing file to your iPhone, in any way, just make sure it's on your iPhone.
Download WireGuard, and SideStore's WireGuard configuration.
Make a QR code out of the configuration and then scan it using WireGuard on your iPhone.
Name and enable the configuration on WireGuard.
Then, open up SideStore, select your pairing file, go to Settings, click the button that says something like "Sign in with Apple ID".
Type in your Apple ID and password, click Sign In and you're done!
Now you can delete the stuff you downloaded, and disconnect your iPhone!