Hey, I'm doing exactly that (keeping a COVID-19 journal with Tiddlywiki). It's mostly not a personal journal, but a collection of everything I learn about the pandemic from news and such, though there's a little personal experience in there too. It's been a great way to learn about the system, as I find more and more things to switch from doing by hand ad hoc to organizing things and adding clever tricks. My most recent triumph was figuring out how to use math filters to create a table of daily percentage increases in cases and deaths, based on entering those in daily tiddler fields. (What a grim thing to have a "triumph" about... but getting these numbers has allowed me to see the positive effect of my state's stay-at-home orders on the rate of increase.)
I find that if I make a collection of all the news I learn, I don't feel like I have to keep it all in my head or post it all to social media or anything like that. I have it set down in a dedicated space where it will be there if I need it.