I'm not sure the part about upgrades including NATO radar or the ability to carry NATO weapons is correct. From what I have read, those items were not included in the modernization. Below is from The Drive, but it is consistent with other sources for both Slovak and Polish Migs.
Slovakia opted for a unique modernization program for its Fulcrums, resulting in the ‘NATO-compatible’ MiG-29AS and MiG-29UBS, with the upgrade being integrated by Russian Aircraft Corporation MiG with participation from Rockwell Collins and BAE Systems, between 2005 and 2008. The aircraft received AN/APX-113 identification friend or foe (IFF), AN/ARC-210 radio, AN/ARN-147 VHF omnidirectional range/instrument landing system (VOR/ILS) as well as the AN/ARN-153 tactical air navigation (TACAN) system. A Russian MFI-54 display and PUS-29 data input panel were provided in the cockpit. The upgraded aircraft, 12 in all, also feature a ‘digital’ camouflage scheme.
They might arrive already prepared for HARM and JDAM, and anything else that has been figured out, so at least "some NATO missiles and bombs". I would assume all of the western air defense systems include IFF, so that feature could be very helpful in reducing friendly fire incidents.
That said, UKR MiGs are carrying HARMs and JDAMs. So, one would expect the Polish and Slovakian MiGs would already be modified to carry HARMs and JDAMs.
Take it up with Denys - he’s the one who said it. Check his comment section and leave your thoughts.
I believe he was talking about the Polish MiG-29s; the Slovakian ones sounded in pretty rough shape from what the War Zone and other have said.