Jailbreak
With recent jailbreaks could be not that easy as it was in the earlier days. Even the simplest things don't work like you expect.
Resign IPA with developer account
This could be problematic due to entitlements. If the application uses them extensively then you would have to create provisioning profile containing all of them possibly also modifying the application binaries as some entitlements can't be recreated as is (like app groups and iCloud containers which are globally unique across all developer accounts).
Free developer account is even worse as it doesn't have access to some entitlements. You would have to examine the application signature and see which entitlements it uses and what the probability that it might work without them. For example, re-signing an app without SiriKit entitlement might cause a crash. When an app tries to access the API iOS will kill it due to missing entitlement.
You might heard about Cydia Impactor which does exactly that. But it actually does a pretty poor job of it. It doesn't preserve entitlements, so there's high probability that the app will crash. Pretty much all remotely complex apps use many entitlements. But it's worth a try anyway.