I won't comment on the broader pandemic response. I hated many of our policies that affected our kids the most, but there were others I thought unnecessary. I do agree the reactions, from both government and citizenry, contributed to a lack of confidence in our nation's ability to govern and thrive.
I share the general feeling of national despair and, as you requested, suggest a few things that the new administration should tackle immediately. I have zero confidence it will do so.
1) National Finances. Deficits and our debt are an existential threat. A reduction in spending should be the priority, but broadening the tax base and increasing taxes on some is also necessary. Areas for deficit reduction include defense spending, more focused international aid, and reducing the size and reach of the Federal government. Debt is a focus on entitlement reduction--phased, focused on those who need it the most, and acknowledging we are able to work longer.
2) Fix Immigration. We need immigrants and we need to be able to absorb refugees. In our welcoming of both, increasing the processing/visa capacity, saying "no" more liberally, and securing the border so we know who is entering are priorities. The border is enough of a danger that it is worth a limited military involvement (combination of active/ reserve/ national guard combined with law enforcement).
3) Re-establish deterrence. The Afghanistan withdrawal and tepid responses to attacks in the Middle East encourage our nation's enemies, especially Iran. A return to "maximum pressure" in terms of sanctions and strikes could be an option. We're on defense now. Continued, even increased, support of Ukraine and Israel. It will be very tough to focus on the significant domestic issues if we are also taking casualties in Middle East.
Healthcare is a topic I've changed my mind on re: Federal involvement, but I would throw healthcare in there as well. Obviously, in a country as large as ours there are numerous problems. Fentanyl, crime, education for example, though I see them as a locally led, Federally supported, effort.