Was Obed-Edom (the Gittite) a Gentile who became a Levite or was he already a Levite when he received the ark?

I recently heard a pastor building his sermon around the 'fact' that Obed-Edom was a Gentile (a precursor to Acts 15:16 - the full inclusion of Gentiles), who became a Levite after the 'possession' of the ark. On the other hand, most commentators claim that he was a Levite from the beginning, though a Gittite obviously being a Philistine, the same camp that Goliath the enemy of David came from. Has anyone studied this in-depth and come to a balanced conclusion? 2 Sam 6:10 >So David would not remove unto him the ark of Yahweh, unto the city of David, - but David took it aside to the house of Obed-edom, the **Gittite**. Barnes: >Obed-edom was a Levite of the family of Merari, being 1Ch_15:18-24; 1Ch_16:38 a son of Jeduthun [*Barnes does not mention the preceding verse 1Chr 13:13 where Obed-Edom was still called a Gittite while he received the ark*], who was a Merarite. [...] He is called a Gittite perhaps from Gath-Rimmon, in Manasseh, which belonged to the Kohathites Jos_21:25. Marriage with a Kohathite, or some other cause, would account for his dwelling in a Kohathite city. Geneva Bible: >Who was a Levite, and had dwelt in Gittaim, (1Ch_15:21). Gill: >... this man was a Levite, as **appears** from his being afterwards appointed to be doorkeeper for the ark, and to sing praise before it, and so a proper person to commit the care of it to, 1 Chronicles 15:18; he is called a Gittite, either because he had sojourned in Gath some time, or rather because he was of Gathrimmon, a city of the Levites, Joshua 21:24. KingComments: >Later we see that Obed-edom gets a special service as gatekeeper at the temple (1Ch_26:4-8). He is a Levite, but born in a city of the Philistines. **His name means ‘servant of Edom’**, that is to say servant of the flesh, the sinful nature, someone who does the will of the flesh (Eph_2:3). But in him we also see what G-d can do in such a person and what His grace can make of him. Matthew Henry: >He lodged the ark in a good house, the house of Obed-edom a Levite, which happened to be near the place where this disaster happened, and there, (1.) It was kindly entertained and welcomed, and continued there three months, 2Sa_6:10, 2Sa_6:11. Obed-edom knew what slaughter the ark had made among the Philistines that imprisoned it and the Bethshemites that looked into it.