Release as such was published on 10th April, thus confirming, for the first time, that Bulgaria may be willing to donate its MiGs to Ukraine. The statement contained in the release, on the replacement of some of the available weapons systems with compatible counterparts from allied nations, suggests that the talks may step beyond the MiG-29 alone, and refer to other types of armament and equipment. These may include vehicles, main battle tanks, armoured personnel carriers, but also Su-25 attack aircraft, or Mi-17 and Mi-24 helicopters.
Not only is Sofia willing to maintain stability in the realm of operational capabilities, but maybe even more, the Bulgarians want to modernize the armed forces and acquire relevant gap-fillers. The above applies to the MRCA domain in particular. The delivery of the latest F-16 Block 70s has been delayed until 2027, while the MiG-29s were expected to be operational until 2023. Furthermore, the jets, maintained in Russia, with inadequate maintenance prices, questionable quality, and with deadlines not being met, led to a situation in which the availability of the Fulcrums also remains low. Thus, a decision was made to maintain the jets in Poland, but it was then sunk and rejected by the Pro-Russian political circles in Sofia. Resigning from Russian maintenance, as NATO member states withdrew from industrial-military cooperation within the framework of sanctions, Bulgaria decided to maintain and repair its jets in Belarus - that solution is also, currently, far from perfect.
Bulgaria theoretically keeps 14 MiG-29 airframes in service now, all of which are more than 3 decades old. Why theoretically? Realistically the availability level is 50% tops, and no more than 2 jets remain ready to fly at any given moment. The remainder of the fleet is being used as a source of spares. That led to a situation in which relevant political decisions had to be made (such as constitutional law changes allowing allied aircraft to use the Bulgarian airspace for Air Policing purposes).
Back in August last year, Krasimir Karakachanov, head of the Bulgarian MoD, announced that a sale of the Fulcrums has been planned, to obtain funds needed to procure another 8 F-16s that would go alongside 8 F-16 Block 70 jets acquired in 2018. Following the September crash of a Bulgarian MiG-29 that crashed into the sea in October last year, Dymitr Stoyanov, the new head of the MoD, announced that Bulgaria would be accepting bids on temporary procurement of MRCA that could act as a gap filler before the F-16C/D Block 70s are delivered. He added that Bulgaria is also talking to Poland about the acquisition of several Fulcrum engines, to extend the MiG-29 operations in 2023.
There is no official information available on the potential bidders, but one may probably assume that Saab JAS39 C/D would be offered by Sweden and Mirage 2000 - by France. Offer regarding second-hand F-16A/Bs (upgraded ones) may be placed by Israel or the Netherlands. Both these nations are withdrawing the aircraft listed above, replacing them with F-35As.
In such a case it is plausible that Bulgaria could transfer aircraft, or other equipment to Ukraine, only after the new aircraft are received. This is a gap-filler solution, but it may last for years, as Bulgaria will not be able to procure brand-new F-16 Block 70s anytime soon. Meanwhile, Bulgaria needs at least 16 aircraft, which is twice as many as the number procured in 2018.