South Korea seem to be able to deliver quite a lot of tanks and self propelled artillery aswell, If I recall correctly both Finland and Poland has bought a lot of K9 Thunder self propelled artillery and K2 tanks. Unsure about the quality of those but I would guess they are on parity with european and american alternatives. Perhaps they can handle some of the backlog.
Technology wise I think the korean options are a little bit behind the US and European options (from what I have been told and have read), but from a quality and reliability standpoint, I believe they are supposed to be pretty good (and fairly affordable) options..
And truthfully, when compared to Russian and Chinese military equipment that they would likely be fielded against, even being one step behind the US and European options still likely places them a step or two ahead of their adversary.. so Korean tanks and artillery might be a good choice for some European countries to consider..
but once again, the problem becomes production capability...
Using the K2 tank as an example.. Poland ordered 183 K2 tanks (order later reduced to 150) in 2022..
Korea will just deliver the first batch of those tanks this year.. and wont complete the delivery of all of the order until 2028..
The K9 Thunder is actually one of the most popular artillery pieces in the world (50% of the worlds self propelled howitzer sales over the last few years have been for the K9)..
Current Hanwah (the manufacturer) production lines can produce +/- 50 K9's a year... and they only export 30 of those units (they keep the other 30 for themselves).. and they are already back ordered for the next 5 years..
So if someone wants to buy K9's.. the absolute earliest you're going to get them is 2030.. and you're only getting 30 of them a year...
and then once you have your K9, what are you going to feed it with? Korea produces about 200,000 155mm rounds per year..
Rheinmetal, which is FAR AND AWAY the biggest producer of 155mm shells in Europe produces 700,000 and supplies most of the EU and European NATO countries..
the US produces 1.2M shells a year... and can fairly easily ramp up to 2M shells per year..
So, even if you buy Korean tanks and artillery.. you're still buying ammo to support those platforms from the US..
Europe simply doesn't have the manufacturing base to support its needs right now..
In 10 years maybe that changes..
but 10 years is a very long time if everyone is legitimately worried about Putins motivations and/or the current war in Ukraine...
Europe may hate that it is going to have to remain reliant on US defense products for the next decade or two (and again, if you're buying US armor, aircraft, missile defense, etc.. you're really signing up for a 20-40 year dependence).. but it really doesn't have another option right now..
Everyone can claim they are going to buy Leopards, and Eurofighters and K9s, etc..
But there simply arent enough to go around.. and the factories cant increase their outputs to meet the needs in a timely manner... its going to be decades before needs can be met by Europe internally.. and by then all of the platforms we're talking about are going to be "last generation"..