The Wrangler has a few high line trim options. The Rubicon is a specialized trim which is sometimes considered high line when optioned correctly. Jeep, as a brand, considers the off-road focused Wrangler Rubicon to be the ultimate expression of a Jeep vehicle. The elements that make up the Rubicon compromise that model for other everyday tasks. There are those who want a V8 Wrangler, but don't want a Rubicon.
Now as far as premium engines in other trims. Chevrolet offers their top truck V8 in baseline trim pickup trucks. Ford offers their Raptor drivetrain in a few other F-150 trims, while they aren't the base models, it still shows up in other trims.
The Jeep Wrangler 4Xe drivetrain is offered on three different trim levels, and the 4Xe is a premium drivetrain option.
Incorrect on both of your examples. GM's "premium" V8 (the 6.2) has historically only been offered in their highest trims. Only recently has it been added to some mid-term trims (RST, LT and custom trail boss). It is not available in baseline trim as you indicate (WT). GM trucks also has no halo vehicle
The Ford raptor HO 3.5 was only added to another of Ford highest trims levels (F150 limited) for 2019. It added dual exhaust as well (i've only seen 1 in person). New for 2021 hybrid option is available down to XL but only crew cab configurations. They have yet to announce 2021 Raptor halo vehicle or what i expect to be its drivetrain but rumors are it will have 2 options - likely H.O. 3.5 hybrid and a halo limited edition run of GT 500 supercharded V8
SRT 6.4 as a premium option i would not expect on lower trims. If the 5.7 was offered i would have expected that on lower wrangler trims as it is elsewhere.
Note that the Rubicon 392 has pulled some things from other trims like Overland. This is currently the halo wrangler like TRX is the halo Ram 1500.
I would agree gladiator mohave would be a perfect premium trim for the 392 to be added to create a "halo" gladiator - i'd expect this will come if/when Ford adds a Ranger Raptor. Currently GM ZR2 does nothing extra in the engine bay nor does Tacoma TRDpro so there is little reason for Jeep to lay down the gauntlet yet on gladiator unfortunately.