@Mame,
Well if Trump were still President, his original sanctions (generally broader than those so far imposed by Biden) on Russia would have been in effect throughout the past year. Their effect is hardly "devastating" as Biden has suggested. However, they would have given us a much more favorable starting point for truly serious additional sanctions now.
In addition, the freeze on the Nord Stream 2 Pipeline would still be in effect and the Keystone pipeline, connecting U.S. heavy petroleum refineries with Alberta, would be operational. We would not have seen Biden's trillion dollar COVID payouts; the needless delay in the resumption of employment it incentivized; and the now 7.5% annual inflation that has resulted from it. Our production of oil and gas, which at the end of Trump's term was 7% greater than our consumption and still rising, would by now be very substantial. That and our continuing construction of LNG processing facilities & port facilities would have given us the immediate ability to very significantly and quickly replace current Russian exports of gas (and petroleum) to Germany and the rest of Europe. THAT would quickly cause very significant and lasting economic consequences for a Russia that is heavily dependent on the revenues from oil & gas exports for its economic welfare. It is at least possible that Trump's continuing pressure on Germany and our other NATO allies to begin investing in restoring their much declined military capability might have yielded some improvements in military readiness in Europe.
All of these things Together would have given Trump (the U.S. and our Allies) a much better hand (and many quickly effective options) for dealing with Putin than Biden has now.
Finally Trump's actions and reactions are a good deal harder for an enemy like Putin to predict than are those of the feckless and incompetent current resident of the White House. That, plus powerful options, noted above and which we don't have now would make for a profoundly different tactical situation for Putin.
Finally, to be specific I believe Trump would pressure Germany to quickly reduce its purchases of Russian petroleum products and finally give up its "special relationship" with Russia, and, if necessary , make a very public issue of it. I suspect he would have by now increased our DEFCON state of military readiness, including our strategic deterrents and reserve forces (that Biden hasn't yet done this is truly both appalling and amazing, particularly in view of Putin's bald threat to impose damages on us "that we have never encountered in our history" if we resist ). I believe he would have also deployed additional forces to the Western Pacific, affirming our support for the continued independence of Taiwan. In addition he would likely have deployed significant forces to Europe, including air and mobile cruise & ballistic missilry capabilities. Beyond that it's hard to tell.
The bottom line however is that with the different initial conditions already noted, Trump's unpredictability and greater inclination to action, I believe Putin wouldn't have decided to invade Ukraine at all.