Error Updating Freeform Pro
Figured it out, posting here in case someone runs into something similar. I opened up the composer.json file in the root and removed the line "solspace/craft-freeform": "2.5.27" from the "required" list.

From there, I was able to update Craft, and then I was able to update Freeform. All is well, and all up-to-date!