My take on the best possible outcome

Yes, there are better possibilities than this, I just don't see them as overly likely.

Senate moderates , especially those up for election, say no appointments before inauguration. Turtles make poor shepherds, and he can't round up his flock.

we end up with 50 or 51 seats. Keep in mind 2016 showed us how much conservatives are willing to hold their nose and vote with a supreme court seat on the line. A seat up in the air will probably put Georgia and Iowa Senate pickups out of reach.

Now we have the lame duck session. Trump, Mitch, and others will be beating the drum to fill it. We will be adamant it should not be filled. The same Senate 'moderates' will wish this would go away.

A deal is cut for the pubs not to fill it in exchange for no court packing and a relatively moderate selection by President Biden. Keep in mind that our control of the Senate is likely to be extremely narrow so packing the court or a very progressive selection would be difficult to get past Manchin, Tester, and Cunningham as they have purple or red state voters to answer to. Garland comes to mind as a compromise candidate.

Sounds absurd? Keep in mind with a nearly exactly divided Senate, both parties will be placing their most vulnerable members in a difficult spot with any aggressive strategy or controversial selections.