If Republican leaders are actually interested in "unity" rather than using its rhetoric to avoid accountability, here's something they could do. It doesn't involve much in the way of consequences, but it does feature truth-telling, apologies and requests for reconciliation.
To be clear, I don't think any of this would actually happen, but it would be nice (if insufficient) if it did.
Ronna McDaniel, Mitch McConnell, Kevin McCarthy, Ted Cruz, and Josh Hawley could issue a joint statement and do a press conference in which they acknowledged that Joe Biden is president-elect and that he won a free and fair election by a sizable margin.
They could say that there is no evidence of meaningful election fraud and that judges, including ones appointed by Trump, have rejected much of what the president and his allies have been complaining about.
They could apologize for misleading their supporters over the past months and say that they understand why Democrats may think their claims fueled last week's violence and are horrified if that is the case.