Sort of; the FEC’s report of the official results of the 2020 presidential election gives an overall figure of 159,752 votes cast for write-in candidates. Unfortunately, their figures can only be based on those reported by the states themselves, and each state has a different way of reporting write-in votes. As I answered to a similar question:
This question is tricky to provide an accurate answer to due to the inconsistencies between reporting of write-in votes. Some states report a total summary figure of 'write-in' votes, in some cases including write-in votes for registered candidates, and in some cases not. Other states provide figures for every separate candidate. As a result, consolidated reporting of write-in figures tends to depend on the methodology of the author.
For a complete breakdown of how many votes each write-in candidate got, you’ll need to look at the figures published by each individual state’s board of elections.
For example, New York State’s results split out the votes cast for each individual write-in candidate, from 999 votes for Brian Carroll right down to 1 single vote for Richard Charles Montanye.
However, if we look at the NY row in the FEC’s report, the votes for Carroll have been split off into their own column, despite being write-in votes in New York, so the overall figure from the FEC is not the whole story.
Furthermore, the FEC’s report omits write-in figures for twelve states, including California, Louisiana, and New Jersey. As far as I know, no complete national breakdown of write-in votes for each candidate has been published.