No. Not even close.

The headline of that article ("US government targets Cop City protester over phone operating system") rests firmly in the lies category of clickbait.

They were targeted for secondary inspection upon their return to the US because they were on a terrorist watchlist, not because they have a phone that runs GrapheneOS.

At least some of what investigators did during that inspection seems likely to be illegal (and the courts will decide if it was, or was not). Meanwhile, the grounds for being on a watchlist to begin with seem dubious at best, as is often the case with such lists.

But none of this was instigated by the presence of GrapheneOS on their phone.

GrapheneOS didn't enter the picture until the person who was already detained and being investigated (and being refused access to a lawyer) provided the phone's duress PIN to nuke the device (by erasing the crypto keys and rebooting) instead of the normal PIN.