Sure, it's a top dog TV, but how likely are they to support the apps you want for an extended period of time? I just want my TV to show a nice picture, I can get all the apps I want somewhere else, likely with a better interface and more long term support. I hardly ever even touch my TV remote anymore. Maybe once every few months I'll drag it out from hiding to tweak some display settings.
Well, Sony TVs are a bit different. They run Android TV just like the shield and in my house is the ONLY TV that doesn't have a shield TV hooked up to it.
Is it as fast as the Shield? No, but my TV is older so the newer OLED may have a better SOC than the shield (probably not) so IMHO if i were to buy a new OLED Sony, I'd use the built in Android TV and if it annoyed me for being slow or apps crashing, then I'd get a Shield TV for it. If it was fast and didn't have issues, no need to fix what isn't broke.
Now, if you want uncompressed HD audio (Dolby TrueHD/Atmos, DTS--HD/X) then the TV won't do that unless it has eARC. In that case, I'd skip the built in Android TV and just get a Shield TV and be done with it.