i had an iphone with i think it was ios 15 or so, i modded it with the
ios cfw.hacks guide, and it worked well. i have an iphone 4 with ios 6 and i dont remember how i did it, i think it was redsn0w or maybe p0sixpwn. the hacking apps all have nerdy names. i dont have the ios 15 phone any longer, but my ios 6 one is still here and i can use my apple account juuuuust fine. i have a tweak that repairs facetime, and imessage worked immediately.
(Unless there is an underground scene of people making modern apps for old iOS versions that Im unaware of?
)
there is a very limited selection of modern appstuffs... i have a
discord client on my ios 6 phone, and i have a
patch for twitter that lets it connect to Bluesky, but i use
BlueBlips on it instead, but thats more revive than backport. i have a tumblr patch that fixes the tumblr app (you can get it as "Tumblere" on the
Bag.XML Cydia repository), i have a mysterious (i dont remember how i got it and i cant find a copy anywhere else, and i cant decrypt it anymore) modded version of Opera Lite that loads even the most modern websites, which i dont use because its too modern 4 mi...
i would recommend you check out
momentum dev, specifically their webapp and "momentum store", the webapp lets you install a very small list of apps directly from your phone, and some are patched, and the "store" (its all free) has a lot of IPAs.
for a specific recommendation, my all-time favorite ios game is
Space Deadbeef, which is really hard to find but which i archived onto iPhoneOS Obscura (or, rather, pointed them to the Internet Archive repositories that had it). my dad used to have that game, and its really hard to find online besides two or three videos on youtube, and at least one of them was made by the developer himself. even worse, its package name is "myfirstbundleidentifier", which is the default (???? why did he do that?), so its hard to search for in directories of archived IPAs, especially if it conflicts w/ other default-named apps.
if you use XMPP/Jabber, i uploaded a
decrypted version of Monal, which i did myself based off of the encrypted version i had on my iCloud account. the app is pretty limited, but it lets you text people and groups, and it has a Jingle-based calling thing but i never got that to work. nobody's told me if the decryption works on other devices, so if you want to veer into the jungle of beta-testing you can try to boot that app and tell me if it works.