GrapheneOS provides massive privacy and security benefits to regular people. That was always important to regular people due to regular devices being nowhere close to good enough to protect people well enough against common threads to their privacy. However, it's far clearer now that exploits have been made so widely available without having expertise. There are many publicly available Android local root exploits on GitHub usable on these devices.

I think it heavily depends. If you are concerned cops or CBP are going to try to take your phone and search it then wanting a phone like GOS is a very reasonable precaution.

Even if you haven't done anything "wrong", you may have engaged in speech or activities that the current US admin has deemed problematic and will try to punish you for if they can find any evidence.

I think this has historically been true and is still approximately true now. But I think in the relatively near future (less than 5 years) there's a really good chance it won't be true anymore.

Once open models catch up to the current frontier in vulnerability exploitation, the cost to target people will go way down. In the past, the cost to hack a random individual person was generally high enough that if there wasn't some special reason to hack you in particular, it wasn't worth it. That may no longer be the case in the near future. The floor of what is acceptable security for the General Public probably needs to rise quite a bit over the next few years.