There seems to be some disagreement on precisely what an EO could or could not do vis-a-vis firearms regulation. Something to think about: even if a law is found to be unconstitutional or illegal, until it is proved to be that (or a process is started to determine that…usually with an order to suspend enforcement pending further court drama), it is treated as legitimate. So, if an EO came through saying something bad, even if it were illegal and unconstitutional, it would still be the valid until the court challenges start.
“The president is going to act,” said Biden, giving some comments to the press before a meeting with victims of gun violence. “There are executives orders, there’s executive action that can be taken. We haven’t decided what that is yet. But we’re compiling it all with the help of the attorney general and the rest of the cabinet members as well as legislative action that we believe is required.”