The claim I responded to was:
1. Android has existing apps.
2. A subset of existing apps will refuse to run on various shades of non-stock/unofficial system.
I pointed out that 1. the existing apps largely do run on other Linux systems via waydroid, and that 2. apps refusing to run on non-stock systems are likely to refuse GOS as well.
If I cut down your page of text to the relevant points, I believe it amounts to:
1. GOS has better app compatibility than waydroid.
2. GOS is supported by some apps that would refuse other non-stock systems.
3. GOS is more secure/private. (This is unrelated and should at most have been a reply to the root comment.)
On 1. compatibility, yes you're probably ahead, though I have to question how much since waydroid is also 90% AOSP. Somewhat similarly on 2. yes GOS has gotten some buy-in, but if 90% is good enough, then again you shouldn't be holding up compatibility as your advantage over waydroid. Basically, either users want 100% app compat - in which case GOS is out - or they don't, in which case waydroid is likely to be an option. Point 3. is irrelevant to the conversation, and you probably don't want to start an argument about general features since GOS is missing vitally important features compared to other Android ROMs let alone "normal" Linux systems (how long has GOS been without full backup functionality now?).
> We've also had to actively convince apps to stop banning non-Google-certified operating systems or to permit GrapheneOS and other secure options alongside doing it.
What other secure options are those?