I am no more concerned about Trump winning than I am about Harris winning. Stein also makes me a bit concerned and I'm not sure on Oliver.
I am far more concerned about the reactions of the American public to either Harris or Trump winning than I am about what either will do as president. Every election since 2000 has had some questioning, each one worse than the last, and we've gotten to the point of division and distrust enough that I'm concerned about how it will escalate this time.
I think it unlikely for Trump or the Republicans to push for an abortion ban nation wide - the Republican base has far too many Constitutionalists who oppose the federal government doing pretty much anything that isn't explicitly listed in the constitution. Their ideal is all the states making choices for their people and people being able to move to the state that fits them best (not a realistic ideal for many reasons, but it is the point of the 'American experiment' as many of them call it), not to make all US states the same. For them, 'returning it to the states' was their big victory.
If the blue wave comes, I am concerned that there will another push against Americans and some US Visa holders who live outside of the US, that the increase in extraterritorial laws that threaten non-US financial institutions to toe ever changing US lines that has already resulted in people having bank accounts frozen and closed, mortgages called in resulting in loss of homes or mortgages refused based on the US connection, jobs lost because we can't have our name on a business account without US law imposed on us, loss of pensions due to the laws on us holding investments. We're now over a year since the US government - having been taken to court over the issue - said they would reduce the renunciation fees back as there was no legal reason for them to hike them as they have, no clue when/if that will happen and while I have no faith of Republicans doing anything on this, it's been when Democrats hold the executive and legislature that these have been brought in and expanded that I fear what further consequences it will have. I think the Greens or Libertarians would be too overwhelmed if they won for this to be a priority, but I wouldn't expect them to support this with their previous actions.
But Harris says she will seek to codify the right to abortion if she wins.
I remember this being promised under Clinton as well. It would be nice if it's true this time, but they have been doing the song and dance about how they need to be voted in so they can protect rights from the big bad Republicans for decades, but they rarely do anything other than inflate their own power.