I don't know how helpful this will be but I'll give it a go anyway. One big difference I can immediately see between us is that you're retired whereas I am not and I find that I'm far too busy at work to think about how doomed the world is. Perhaps a hobby you can really lean into would serve the same purpose for you?
As far as social media goes I was already only on Reddit until the great exodus. By the time I found Lemmy I was already out of the habit of going onto Reddit every day and I've noticed since then I have been a lot better at ignoring the political stuff that comes across my YouTube feed unless I specifically feel like watching it.
I've been dealing with depression a lot longer than there's been an oompa loompa in the White House but I actually find it's been easier to deal with since I've been working more and distracted less by social media.
Again, I dont know how helpful you might find this but I figured it was at least worth mentioning what seems to work for me. Perhaps you might find a mix of several answers on this thread works for you. You can't solve the problems of the world but there is always a way to feel better about your little corner of it and yourself as a whole.
Edit: just wanted to clarify I'm not suggesting that you lose yourself in work to block out the noise of the world, rather that it makes the free time you do have far too precious to spend worrying about things that are well outside of your control.