The widespread meaning amongst the commentators is that even though idol worshippers do not worship G-d, they still recognise Him as the ultimate G-d.
Refer to Rashi who notes:
My Name is great among the nations - Our Sages stated (Menachos 110a): For they call Him the God of the gods. Even one who has an idol knows that He is the God Who is over all of them - and everywhere they donate in My Name. Our Sages, however, explained: These are the Torah scholars who are engaged in the laws of the Temple service everywhere, and likewise, every prayer of Israel that they pray anywhere is to Me as a pure oblation. And so did Jonathan paraphrase: And every time that you do My will, I accept your prayer, and My great Name is sanctified through you, and your prayer is like a pure offering before Me. This is the explanation of the verse: Now why do you profane My Name? Is it not great among the nations? As for Me, My love and My affection are upon you wherever you pray before Me, and even in exile, [offerings are] burnt and offered up to My Name. (Sefaria translation)
Malbim explains that the non-Jews acknowledged that there was a greater power over them - a אלהא דאלהיא - a G-d over gods. However, they believed that the relationship was such that He ruled like a King who delegated jobs to his ministers and servants. As such, G-d wanted them to be given honour as they are the ones who approach the king and are the means between Him and the people. In other words, their honor is the honor of the king.
Similarly, Radak notes that they acknowledge G-d as the first and greatest G-d but they see other forces as being His intermediaries.
(See Rabbi Yehonason Eibschitz in his Ahavas Yehonason for a similar approach).
The Metzudos Dovid notes that all the non-Jews acknowledge that G-d is the sole influence and reason for all. However, they believe that the running of this lowly world has instead been passed on to the constellations etc.