True! 
I’ve used it with M1, M2 and Wordpress with no problems. I think the only problem you might have would be if it’s not a popular template you’re using, there might be conflicts that have never been encountered before. Porto & Ultimo will have all the issues pretty well documented I reckon.
I only learned earlier in the week that Ultimo is dead now. Not been updated since Jan 2019 if memory serves. Pitty really. And none of the M1 top seller themes have an M2 version for some reason 
I dabbled with Ultimo and M2, it was a nightmare. Spent so long fixing bugs I ended up getting rid of it completely. Shame as Ultimo was brilliant. Theme Forest is full of people who have bought the theme and are angry that it doesn’t work. I feel sorry for them, but also don’t part with cash until you’ve read the most recent reviews!