Both Walker and DeSantis had/have messaging problems. Walker was a good governor but didn’t really have any vision for what he wanted to accomplish on the national stage. I always felt his heart wasn’t really in it, and that he ran because it just seemed like the next logical career step for him to take.
DeSantis also has a messaging problem. He’s trying to beat a very popular front runner by adopting most of that front runner’s platform and claiming that he’s just a better version of him. That strategy gives you very little to work with. You can’t attack the front runner too hard or you undercut your claim to being similar to him and you alienate his supporters, which you can’t afford to do. On top of that, he has a past history of supporting Trump which makes any distancing of himself from him now, seem opportunistic.
My sense is that Walker is more trustworthy and principled than DeSantis, but he really had no great interest in becoming president. But aside from that, their campaigns are similar.
I think it remains to be seen if Trump can win another national election. Unfortunately, I suspect the answer is no.
He was able to beat Hillary, but in many ways, he got lucky. Virtually no one expected him to win, which is why the Dem machine was not mobilized the way it was for Biden. Indeed, the Dem machine and the elites pulled out all the stops to ensure Biden won, including unleashing CV-19 (which I still think was NO accident and done for political purposes).
Of course, I am not sure any Republican could win. The Dems learned their lesson from 2016 and will not be asleep at the switch again. Aside from Trump, DeSantis has the best chance.