You can install slightly older signed versions (usually 1-2 months old) using supervised mode and DelayOTA profiles. Not truly unsigned – Apple still signs these temporarily.
When searching for "free unsigned IPSW restore," users often encounter scams. unsigned ipsw restore tool free
A: No. Download your IPSW from IPSW.me or Apple's official servers. Verify the SHA1 hash before restoring. You can install slightly older signed versions (usually