We’ve got a couple of Frames, and yeah those two-piece mounts are way different…but a huge part of why you pay a premium for them. They’re also nerve wracking trying to snap the tv into/out of.
So there are absolutely no studs that’d cross behind any of the holes in either mount? I assume your stud finder works on wood paneling and you double checked by measuring 16” centers starting from that outlet box down there (whichever side the stud is on).
What’s behind that paneling…anything? Pop the cover off that outlet to see if you can verify how thick it is and what, if anything, is behind it.
As you noted, the tv itself isn’t that heavy since all the guts are in the OneConnect breakout box. If that paneling is actually mounted to studs securely, I’d like to think a gang of good toggles would work…but obviously having at least one mount hit a stud would be peace of mind
The best anchors I’ve seen are WingIts, though they require using a special 3/4” bit to put the hole (don’t use a spade bit on that nice wood).
Otherwise, per usual, best reply is the first: get serious by running a 2x4 horizontally and call it a day.