What would have happened going into the 2021 presidential inauguration if sealed indictments were filed while Trump was POTUS against every person in the line of succession to the Presidency? Specially for treason.

And what if they weren't ready to unseal them at that point?

Who would the military consider Commander-in-Chief? What would they do?

In the TV series Designated Survivor, a third party, an independent, became president after all of congress, judicial, president blown up.

The series coincidentally comes out as Trump runs for President.

Blowing up the line of succession doesn't have to be physical - treason would have the same effect.

Current line of succession in this link:

https://en.wikipedia.org/wiki/United_States_presidential_line_of_succession#Current_order_of_succession

If they are all charged with treason (sealed indictments) could any of them be acting-president?

The Presidential Succession Act refers specifically to officers beyond the vice president acting as president rather than becoming president when filling a vacancy. The Cabinet currently has 15 members, of which the secretary of state is first in line; the other Cabinet secretaries follow in the order of when their departments (or the department of which their department is the successor) were created. Those heads of department who are constitutionally not “eligible to the Office of President” are disqualified from assuming the powers and duties of the president through succession, and skipped to the next in line.

https://en.wikipedia.org/wiki/United_States_presidential_line_of_succession#Current_order_of_succession

Talk about a constitutional crisis!!

Would the top military have decided to let Biden pretend he's president in order that our enemies abroad not realize there is no commander in chief?