Agree with the answer, and would like to add the reasoning behind the "pardon" based on the official documents. The reasons for the pardon of R. Hunter Biden, as indicated in the documents primarily revolve around the belief that he was selectively and unfairly prosecuted due to his familial connection to the President, and that raw politics infected the process.
Specifically, the reasons include:
Selective and Unfair Prosecution: President Biden stated that his son was "selectively and unfairly prosecuted". He noted that people are almost never brought to trial on felony charges solely for how they filled out a gun form without aggravating factors like use in a crime, multiple purchases, or being a straw purchaser. He also highlighted that those late paying taxes due to serious addictions, who subsequently paid them back with interest and penalties, are typically given noncriminal resolutions. It was clear to him that Hunter was treated differently.
Political Instigation and Pressure: The charges in Hunter Biden's cases allegedly came about only after several of President Biden's political opponents in Congress instigated them to attack the President and oppose his election. Furthermore, a carefully negotiated plea deal, agreed to by the Department of Justice, unraveled in the courtroom, with a number of political opponents in Congress taking credit for bringing political pressure on the process.
Singled Out Due to Being the President's Son: President Biden believes that no reasonable person looking at the facts could reach any other conclusion than that Hunter was "singled out only because he is my son, and that is wrong".
Effort to "Break" Hunter and the President: There has been an effort to break Hunter, who has been 5½ years sober, even in the face of unrelenting attacks and selective prosecution. In trying to break Hunter, they've tried to break President Biden, and he believes it will not stop there, stating, "Enough is enough".
Miscarriage of Justice due to Politics: President Biden stated his belief in the justice system, but also his conviction that "raw politics has infected this process and it led to a miscarriage of justice".
Sources:
1) Judge Scarsi, ORDER RE: NOTICE OF PARDON,
https://www.documentcloud.org/documents/25444472-2024-12-03-judge-scarsi-hunter-biden-pardon/
2) Statement on the Presidential Pardon for R. Hunter Biden,
https://www.govinfo.gov/content/pkg/DCPD-202401043/pdf/DCPD-202401043.pdf