I see that i have made this type of suggestion a long time ago, but i thought i would remake it.
I do think portal chests should be in expert mode, but they should be an endgame item. meaning you can only craft them in the endgame. As they would have the same data as a normal portal chest.
To craft a portal chest you can find it in the workbench under level 30 which would be a new upgrade. to upgrade your bench you would need 1 portal and 1 diamond, that is it.
Then to craft the portal chest it would be in two parts, a deactivated one and an activated portal chest.
To craft the deactivated portal chest you will need 10 diamonds, 1 diamond portal, and 1 gold chest.
This portal chest would not be active, so in order to activate it you would need to tap on it and feed it 100 time crystals to stay alive for 24-48 hours. Once it dies you will need to once again feed it 100 time crystals.