Yes. Yes they have. the linked article mentions a few. Maybe you should put them in touch with that Walsh character.
Also from the linked article, you can see that Trump has commited like Biden has:
Smith then said, “The question was, is it a consideration to skip the debates?”
“And my answer is we are very much looking forward to debating Donald Trump,” Bedingfield [Biden's comms dir] responded.
In a statement sent to Fox News, Trump 2020 campaign communications director Tim Murtaugh reacted to Bedingfield's comments saying, “Joe Biden is the only one who is being coy about showing up for debates and he is the only one getting public advice from his supporters to dodge them.”
“President Trump is looking forward to debating Joe Biden,” he continued.
Link: https://www.foxnews.com/media/biden-campaign-official-trump-debates