I own this game on steam and it is actually almost drm-free even on steam.
They only put a steam api call for multiplayer/achievements/save cloud... when it fail the game does not start... but with a simple steam api open source alternative it will work without any issue.
The executable is not even encrypted like most game on steam, so it does not even have the basic steam drm (just an api call that act as drm).
I really do not understand why this great game is not here on gog. It is a game that you can play offline, without any microtransactions, with a modern but classic feel and a lot of cards.
I actually cannot even believe konami made this game on pc because before this game every game without microtransactions and always online was on console, and the game after this one on pc (master duel) is still always online and with a lot of microtransactions.
Basically this is a real exception. Also since it was recent if you did not start to play the game recently you should be able to make your real deck inside the game. But that's not all, the AI of this game is not bad at all, and with the steam api alternative you can even play with your friends in LAN and with pixeltris/Lotd you can even use your own custom deck against each other playing against the AI that will use the deck in a good way (not as good as a human of course but much better than most AI out there even the AI of EDOPro).