The Magura MT7 uses a pad shape that's shared across quite a few of their 4-piston calipers, and you're right that there are aftermarket options out there from the likes of Uberbike, SwissStop, Trickstuff, and a few others. Whether they're literally the same compound rebadged is one of those persistent rumours that's hard to fully confirm, though it's widely believed that some OEM pad manufacturers do supply multiple brands.
Additionally,
@Singletrackmind, there's a fair bit of real-world data floating around on this. First, a quick primer on Magura's own naming: the number indicates the shape of the pad and the colour indicates the compound. For your MT7's 4-piston calipers, variants with "8" and "9" are compatible with 4-piston calipers (MT5, MT7, LOUISE). So you're looking at the 8-series pad shape. Your Sport (green/8.S) and Performance (grey/8.P) are both organic compounds, with Magura's pads made of an organic pad compound with a metal content of up to 30%. The Performance sits a step above the Sport in terms of initial bite. Above that sits the 8.R (Race), which is their most aggressive option.
Now, the aftermarket scene. The pad shape itself is shared across the MT5/MT7/MT Trail front caliper family, so there are direct replacements for Magura 8.1, 8.S (Sport), 8.P (Performance) and 8.R (Race) disc brake pads
from various manufacturers. The names that keep coming up in community discussions are Galfer, MTX, Uberbike, Truckerco, EBC, Disco, and Miles Racing. Galfer Pro pads get particular praise, with riders reporting strong performance especially when paired with Galfer's own rotors.
MTX Golds also get a solid endorsement for front and rear, and Truckerco pads have been used on multiple sets of Magura including MT7s with good results. Uberbike e-matrix pads (4pc design) are another option that riders are running on MT7 calipers. On the sintered side, EBC brake pads with the sintered compound (the orange one) are recommended for longevity and wet grip. As for the "same pad, different label" rumour, it's plausible for some of the budget options since there are only so many pad factories in the world, but the compounds from Galfer, Trickstuff, and MTX are generally understood to be their own formulations. The biggest difference you'll notice going aftermarket tends to be in compound choice rather than brand loyalty, specifically whether you go organic, semi-metallic, sintered, or ceramic. Given you're riding in San Diego's mostly dry conditions, organic or semi-metallic will serve you well on the front where you want that strong initial bite, while a slightly harder compound on the rear could give you better longevity without sacrificing much.
One thing worth flagging from our community knowledge:
@Astro66 made a good point that aligning MT7 calipers is fussier than Shimano. If you swap pads and notice any drag, it's worth checking alignment by eye rather than relying on the "loosened bolt squeeze" method that works on 2-piston calipers.
I've got some data on Magura bleeding tips and caliper alignment quirks if you want to go deeper on the maintenance side.