The thing you have to understand about UM is that a lot of it never really directly connects, or was a reboot at some point, or seems out of place. Certainly, with statements regarding The Mummy (2017) and the Dark Universe park, plus the footage they used for it, it is definitely one universe now, even though some connections are less sustainable than others. Fun fact, the audio short story on this timeline set in the 1940s titled Halloween Horror Nights: Echoes from the Fog 1x04, "Universal Monsters: Eternal Bloodlines" ties to an amusement featuring the Classic Monsters, particularly Dracula's Daughter. There's easter eggs to Abigail in it, which is confirmed Universal Monsters in interviews too.
Some content is more distant and less connected than others, while sometimes it is. The Mole People had absolutely no connection until the new park referenced it, but it was always part of the universe. I would expect nods to other things too, honestly.