There actually was a crossover with the two series in Imaginary Fest where Nazarick meets ITEM. Thankfully, Ainz was only dealing with a relatively minor faction on the Science side rather than any heavy hitting mage for the Magic Side
And even then, Narberal was pretty close to getting her shit kicked by Mugino once she got tired of listening to her endless talk of her and Ainz’s superiority over them.
Also, get ready for the upcoming Overlord movie which will feature such wholesome content as Demiurge kidnapping and forcing mothers to eat their own children and breed them with monsters to produce chimeras in his “skinfarm” he maintains just outside the Holy Kingdom all just for sick amusement and the Queen of that kingdom for the crime of being one of the few decent people in the entire setting and opposing Nazarick, getting used as club for several days straight to kill her own people with by a big ass demon before she’s able to die from the injuries.
Because the author has a real boner for condemning the good but too weak to do anything people in this setting to the most horrendous/degrading deaths he can think of.