Outside of voting, you have options. I’m not American, but I’d advise any communists to vote Biden simply because the repression under Trump could get really ugly, hindering any proper organisation. Just view it as what I think it also actually is: A cynical, pragmatic move to save you and other working people from more open repression, nothing more.
But before and after voting: Put your energy into unions like the IWW, into neighbourhood organisations for mutual aid, into community defense like the SRA or Redneck Revolt, into antifascist organisation, into refining your own position and presenting it to others. Create networks and connections. All preventing Trump is doing is buying time for now to do exactly that. Things will only get worse in the decades ahead, with no end in sight for the climate catastrophe and further decay of capitalism - and laying the groundwork of actually being able to do something is critically important right now, in my opinion.
Of course everyone is in the end their own master when it comes to decisions like this. Just - remember that by not voting in this specific election you also aren’t changing anything. And while I fully understand the desire to organise for a third party, they have been marginalised effectively, at least I personally don’t think electoral politics will bring any relevant changes, one way or the other. They are just about who carries the whip used against you, and in this case if the are openly and harshly, or covertly and less efficiently using it.
That all being said - I think a few people here overestimate the amount of tankies and communists that won’t vote Biden. The group is marginal in the big scheme of things. If Biden loses, you can be certain, they were not responsible, they are most likely less than 1% of voters. Personally, I’d blame the corporate core of the Democratic party and middle class liberals for being out of touch with reality.
So, take this point of view as what it is: a view on the situation from an outsider, I am not American, I am a German communist. While I do probably look more closely at American politics than most likely the average American simply from being interested in politics to a pathological degree, I might not have the full picture of an American who is also as interested in politics.
I think in this particular moment, as much as the Democrats do their best to antagonise you, as much as you are correct that someone like Biden will continue with the same status quo bullshit that created the situation to begin with, as much as he won’t be helping the people suffering from (neo)-colonialism in a meaningful way overseas - I don’t think that this particular election is the time to vote third party. The chance may come, and best then to do it not as individuals based on your personal conscience, but as an organised group, with concrete messaging communicated. And even in other elections and outside this vote, organising for a third party - while I personally don’t have a lot of hope for electoral politics - is certainly better than investing energy into the Democratic party, whose supporters seem to have no problems spewing hatred towards you for not agreeing with their party line and view of reality.
But I think underestimating Trump could be genuinely dangerous. Not because he will “ruin America” or anything like that. Simply, because he will be in a position to dial up repression, potentially leaving you with a situation in 2-4 years, where the party you voted for has to move underground, either having gotten outlawed or further marginalised and infiltrated. The situation looks critical enough to me, that under a Trump presidency, unions and leftist orgs will face open persecution much more than under someone like Biden - who is admittedly bad enough. Persecution up to outright criminalising them, to encouraging right-wing militias to kill their members with a slap on the wrist as a consequence or no legal repercussions at all. Yes, I do think that is unfortinately a realisitic possibility. And at this point, I don’t think leftist orgs in the US have the resilience yet to efficiently organise in the underground.
That being said, I won’t tell you a vitriolic “you will be at fault” if you choose to vote and organise as you want to. I do also see advantages, like getting visibility for your issues and potentially by reaching certain threshholds getting public funding support and the likes (that exists in the US too, right?). But I’d still advise it in this election - as shitty and cynical as it is - to vote for the old fart that doesn’t swing the whip of the state as hard on your back as the one that might outright strangle you with it. Getting a proper communist, grassroots organisation running in the United States is important for the whole world, and I fear it will be impossible, or at least much, much harder under Trump (mostly, again, because there are no proper structures in place to move into illegality and organising underground, from everything I can tell.)