thechosenjon I'm not sure I follow... if running the diagnostics confirmed a manufacturing defect, the phone would be wiped and sent to Google, no? So it seems as if the need to wipe the phone may be a consequence of the defect.
Like other Google features, I expect that if repair mode can be integrated into GrapheneOS with reasonable development and maintenance costs then it probably will be, but maybe after a significant delay if it's a lot of work. But, like some Google features, if it can't be integrated (perhaps in this case due to being a closed-source proprietary blob), then it probably won't be.
Filing an issue on the GrapheneOS issue tracker might be productive.