Denmark, Netherlands and Germany are working on this project since Feburary as presented in the OP.
The 100 German Leopard 1 tanks were a part of the 120 Leopard 1 tanks previously in service with the Denmark Army. The retired Leopard 1 tanks of the Denmark Army were refurbished before they were retired.
Denmark confirms that 100 Leopard 1A5 tanks for Ukraine will be ready in the spring
Danish army Leopard 1A5DK Main Battle Tank MBT. (Picture source Aalborg Defence and Garrison Museum / Denmark)
According to a statement released by the Danish Ministry of Defense on March 11, 2023, Denmark has confirmed its collaboration with Germany and the Netherlands to donate 100 Leopard 1 Main Battle Tanks to Ukraine. Following a visit to the German company FFG (Flensburger Fahrzeugbau Gesellschaft mbH), Danish Defense Minister Troels Lund Poulsen and State Secretary from the German Ministry of Defence, Thomas Hitschler, confirms that the German company FFG works to refurbish Leopard 1A5 tanks that were previously in service with the Danish army.
In early February 2023, Denmark, together with the Netherlands and Germany, launched a project to refurbish a large number of Leopard 1A5 tanks. The first goal of the project is to deliver two tank battalions to Ukraine as quickly as possible, which corresponds to approximately 80 tanks. The first tanks are expected to be ready during the spring and will be used to train Ukrainian forces. As part of the project, Denmark will provide training to Ukrainian soldiers on how to operate the Leopard 1A5 tanks, as well as supply spare parts and an ammunition package. Citing information reported by the Army Recognition editorial team the German company FFG has a stock of 100 Leopard 1A5 that was purchased in 2010 from the Danish government. Denmark ordered 120 German-made Leopard 1A3s in June 1974, the first of which were delivered in March 1976 and the last in November 1978. Denmark modernized the Leopard 1A3 to the 1A5 configuration and named Leopard 1A5DK.
Cool on NATO and EU with the USA.
Denmark btw is known in NATO as "Little Sparta" because despite the small size of their armed forces, they are skilled and fierce fighters in NATO missions abroad.