Accepting a pardon is an admission of guilt. So, if Trump took a pardon from Biden, it would be Trump admitting he did whatever he accepts the pardon for. 

There have been people saying since Biden was elected that he should issue Trump a pardon. I believe this is because there is a school of thought that you don't carry out punishment against a president, you pardon them for the good of the nation. Not that we have had many presidents in need of pardons, but Trump is a long-term criminal and repeat offender so if anybody needed a pardon, it would be him. 

I don't think Trump would have ever ended up in jail anyway. He would have always got some sort of special treatment because he was a former president. Plus some of the crimes he committed, he could have easily negotiated his way out of but this guy just won't admit to wrongdoing of any kind. He always has to portray himself as the greatest, best, most amazing ever. Arrogance and stupidity are his most potent qualities. 

The reason for Biden to pardon him would be that some sort of deal was made with Republicans not to go along with any of Trump's own revenge schemes over the next 4 years. Problem with that is, you'd have to trust them to hold up their end of the bargain...and they have shown no, I mean zero, evidence they should be trusted. 

You can't broker a deal with Trump because he does not believe in deals. He thinks suckers make a deal, and he would only make one with you to screw you on it. 

Probably best not to pardon him because then his crimes continue to hang over him with the potential to haunt him and what he tries to do in different ways.