I happen to live in a different area, where those opinions are held by 100% of the people I know. I have never seen a pro-Biden sign. I know lots of real humans who are very angry that they always get flagged as being bots. No, they aren't bots.
I wonder if you will dismiss me as a bot. :-) Denial of the existence of Trump supporters is a really strange phenomena. What drives it? Of course these people exist! Denial is how people thought Hillary would win. If anything, Trump has more support in 2020 than he did in 2016. Among republicans, the doubt and mistrust is gone.
Note that you can't even see much of the Trump/anti-Obama/anti-Biden content. Both https://kamalaharris.info and https://joebiden.info have been blocked on Instagram, even in private messages. The sender sees it as sent, but the receiver never gets it. Those aren't malware or scams or anything like that. Those are well-researched opposition sites that even have references, put together by a really dedicated Trump fan.
So the true extent of Trump support is just hidden. You can't see it. You may find yourself having a really big surprise on election night.