Re: Tehilim for Trump.
First, it may be late to question the tehilim, they apparently worked. So you probably wouldn’t want to retract tehilim after Hashem accepted them.
2nd, President Trump did use multiple measures: frequent rapid tests for himself and others around him; social distancing for everyone else. Secret service is great at enforcing social distancing. How does the psak apply in such a case? For example, to shlimazels who wear mask on one of the two face orifices or take the mask off to talk to others.
3rd. We might have different criteria for heads of state. Jews prayed for health of various kings and emperors, many of whom were involved in pretty unhealthy activities