Saw it mentioned in a different post. “The Doctor of Missiology (DMiss or D.Miss.) is a doctoral degree in the field of missiology.“ https://en.wikipedia.org/wiki/Doctor_of_Missiology
This Adventist School apparently turned their DMiss into a Doctor of Intercultural Studies. https://www.andrews.edu/sem/dis/index.html This one is either or and lays out a curriculum. https://www.aiias.edu/academics/theological-seminary/doctor-of-missiology/
Evangel also changed the name of their Doctor of Missiology program to Doctor of Applied Intercultural Studies https://www.evangel.edu/programs/applied-intercultural-studies-seminary/
Here is a UK school with a PhD in Missiology in partnership with the University of Manchester. The PhD in Missiology is considered a professional doctorate. https://www.cliffcollege.ac.uk/courses/undergrad-postgrad/pgr-research
They're regionally accredited, and they charge $500 per credit for 48 credits for a total of $24,000. Not bad, although they do require a number of visits to campus.