Here's how I imagine things could play out:
1. For things to go smoothly, we need a significantly earlier Győri Program, maybe starting from 1936.
2. During the Anschluss, Hungary have to make a very risky move. When Germany begins to occupy Austria, the Hungarian army also needs to move in and occupy Burgenland(Hungarian until Trianon) then demand an option on the referendum for Burgenlad to join Hungary. If things go well (let's assume) Burgenland chooses Hungary over Germany. The Hungarian army supervised the referendum there so it shouldn't be that hard.
3. Hungary should attempt to have the OTL First Vienna Award to be included in the Münich Agreement. This way, the revision is less seen as a solely German act of generosity, which this way wouldn't "indebt" the Hungarians to the Germans.
4. When the Germans invade Czechia and create the Czech-Moravian Protectorate, Hungary should also invade Slovakia alongside with the OTL invaded Subcarpathia. The Hungarians now might not be so submissive to the Germans, but still this might improve Hitler's view on the country, who was annoyed by the Hungarian reluctance to fight IOTL.
5. WWII breaks out, let things go similarly to OTL, except, that the Germans can't invade Poland from Slovakia. Also don't alienate the Allies by publicly congratulating Hitler for the successes on the Western Front.
6. Threaten war with Romania, Germany will be forced to interfere to maintain a secure flow of Romanian oil. OTL Second Vienna Award is TTL (first and last) Vienna Award. Join Tripartite Pact(Axis).
7. Have PM Teleki Pál not commit suicide, only resign. Participate in the invasion of Yugoslavia, but only after Croatia declared independence, so you technically don't break the eternal friendship treaty. Wallies break diplomatic relations, but do not declare war.
8. Get back Teleki as PM and do not join the war against the Soviets. Hungary would have to allow the German usage of their railway network though. From now on, play the Swede.
9. 1941-'42, due to the increasing difficulties, Germany demands Hungarian entry, but only some volunteers are sent. Also production of war products for Germany is expanded, mainly by German licenses. (Steal technology.)
10. As Soviets are closing by, the Germans begin to fear being cut from the Romanian oil fields. Plans to invade Hungary are initiated.
11. Operation Margarethe(the plan to invade Hungary), since it would require a significantly bigger army than IOTL is delayed because of the urgent need of troops against the Soviets.
12. In mid-May, Operation Margarethe begins, drawing Hungary into the war on the side of the Allies. The Hungarians were prepared for the German attack, which they were aware of. The additional years of infrastructure, arms industry and army building of the Győri Program will have a great significance from now on.
13. German offensive bogs down on Vág and Rába rivers to the West, in the Carpathians to the North and Northeast(Árpád Line). The auxiliary Romanian attack from South Transylvania is also stopped, while the Drava and Tisza rivers are preventing the Germans to launch successive offensives from the South.
14. After the failed German invasion of Hungary, D-Day and the current German defeats against the Soviets, the Romanians change sides a month earlier compared to OTL, which with the Hungarians simultaneously launch their offensive to occupy South Transylvania. As a result, almost all remaining Axis forces in the area are destroyed. The minimal Soviet involvement in the action is just icing on the cake.
15. As the war progresses, Hungary eventually occupies West Banat, Srem and Slavonia(the area by modern definition) and slowly begins to retake the lost West Danubian territories.
16. The war ends with Berlin falling to the Soviets, the WAllies liberating everything until the Elba, a Czech uprising(with Hungarian assistance in Moravia) succesfully clearing the German soldiers from Czechia and the Hungarians taking Vienna. The Germans unconditionally surrender.
17. Hungary at Potsdam and at the peace treaties gain all of its territories lost in WW1 with the exception of Croatia-Slavonia and Fiume, which become part of the new Communist Yugoslavia. Yugoslavia also claims Vojvodina and the Baranya Triangle back, which remains in Hungarian hands. A fierce rivalry, a mini-Cold War begins between the two. Hungary also gains the right to participate in the Allied occupation of Austria with its sector consisting of Lower Austria and Vienna(so basically the Soviet sector of OTL). Czechia is formed, which gives up its claims to Slovakia and Subcarpathia.
18. Miniscule border adjustions with Poland.
19. ITTL, the Soviet reach is somewhat smaller compared to OTL with East Germany, Poland, Romania, Bulgaria and Albania becoming their puppets by the beginning of the Cold War. Yugoslavia is also communist, but just like OTL, they become non-aligned. Hungary, Czechia and later the reformed Austria also become non-aligned.
20. In the early 60s, Horthy dies. With the significant internal support for monarhcy and with the Habsburgs no longer being viewed as a threat by external elements, the legitimist manage to invite Otto von Habsburg to the throne. With Otto's reign, a democratisation and liberalisation process also begins. Reconcilation with the minorities and a meaningful minority policy are also begin to be developed.
21. The Habsburg reinstallment summons loyalist zeal in the people of Austria and later also in Czechia(unexpectedly), and the Habsburgs are also reinstalled there. The three pivotal countries of the old danubian monarchy are once again under personal union, which also marks the start of a Central European development similar to the EEC( later EU) of Western Europe.