Well, I found what nvidia is checking. And it might be a major pain to change. Tegrazone is parsing ro.product.name (cm_roth for my builds, thor for stock). I don't know if I can override that or not. But if any of y'all want to tinker with it, you can change the build.prop line to 'thor'. Unfortunately, that doesn't fix the problem here. Even with Geforce Now showing up, it fails to run a game. The libs failing are the ones shipped with the apk (libadaptordecoder23.so). There seems to be one per android api level. It tries to load the api level appropriate one, then falls back to one in the rom. Unfortunately, I can't seem to even get the one from level 22 (L) that works on 12.1 to load. And no log messages. Not sure what's failing and without inside help, I might never figure it out.
In other news, I finally got my hands on the beta libs. So far seems so good. The volume does seem to fluctuate slightly, but no where near as bad, and tends to go down more than up, so it doesn't jump up and scare the daylights out of me anymore. I'll continue testing over time and when Nvidia officially releases the update, I should be able to roll the changes into CM pretty quickly.
Edit: In other interesting finds, here's a list of supported devices:
thor, thor_hk, foster_e_ironfist, foster_e_ironfist_hdd, darcy_ironfist, foster_e_ronan, foster_e_ronan_hdd, darcy_ronan, loki_e_wifi, foster_e, darcy, foster_e_hdd, wx_na_wf, wx_na_do, wx_un_mo, wx_un_do, wx_diag, sb_na_wf, he_na_wf, he_na_do, he_un_do, he_diag, loki_e_tab_os, ga_na_wf, ga_diag
Side note: I've barely seen any of the Marvel movies and read none of the comics, so I've not put together the pieces until recently... Anywho.
So, thor is the Portable, foster is the console, and wx's and sb are the current tablet (does anyone actually know what wx is a reference to?). Darcy iiuc is a dev board for the t210 chipset. Ironfist and ronan are recent sub-sets that I haven't quite pinned down yet where it's going. Loki and HE are the interesting bits. Loki has been a long time coming and we're still waiting. That elusive Shield Portable successor. But I keep seeing more and more references to it. There's an awful lot of of code support floating around for it for them not to release it... Then he is Hawkeye, according to the aosp code release an X1 tablet with many of the same specs as the current gen, but the soc that the console has. The other interesting bit is the editions. loki_e_wifi and loki_e_tab_os. The aosp code drop has a couple more versions like an lte model (I'd sign up for that...), but this indicates only a wifi model. The second one points to an interesting assumption: tablet os? So that means the standard install is something else like android tv? With a controller interface, that could be useful and with the option of a standard android install, possibly with dual boot, I'd be for it. Then the Hawkeye's have the same as the current set of tablets, even though wx_un_mo is listed (wonder who actually has one for it to still be in the code, not the software division I had contact with). Finally there's the ga. First reference I've seen of it and the last in the code list. Possibly some new device there isn't any leaked info on yet.