I think that would be difficult to achieve. If it's minimal enough to achieve the goal, it's minimal enough to look like travel mode.
If the only goal is to refuse them access to your account, you can do that already. Your devices will be confiscated, non-citizens will be refused entry, but you can do it if your device encryption is strong enough.
The goal here seems to be to give you the ability to get through the border without giving up your information. If it looks like "trip mode", it's failed at that goal, and I'm not sure it's possible to make it both mainstream and stealthy enough to work.
If the only goal is to refuse them access to your account, you can do that already. Your devices will be confiscated, non-citizens will be refused entry, but you can do it if your device encryption is strong enough.
The goal here seems to be to give you the ability to get through the border without giving up your information. If it looks like "trip mode", it's failed at that goal, and I'm not sure it's possible to make it both mainstream and stealthy enough to work.