My understanding is that you can still do a person to person firearm sale for non-prohibited items using the ISP website. The buyer that has to take a copy of that ISP approval form and store it with an FFL for 10 years. Or you can always transfer it in the presence of an FFL
https://verify.ispfsb.com/Public/Verification.aspx#:~:text=430 ILCS 65%2F3(a) - "Except as,valid Firearm Owner's Identification Card