They are still mercenaries no matter how you want to try and twist it.
If non mercenaries are to be called mercenaries then what do we start calling the actual mercenaries?
This is from the legal education part of West Point from March of 2022 when the Reddit people were volunteering, and since then Ukraine has done more to make sure that none of its forces can be called mercenaries if captured by Russia.
“A member of the armed forces of a belligerent is not a mercenary. The Ukrainian government has formally incorporated the International Legion of Defense of Ukraine into its armed forces. Thus, the Legion’s reported 20,000 foreign members—including 3,000 Americans—are not mercenaries”