You’re not mistaken, it is definitely possible with at least RSA, though, I would guess it may not always be possible. It also sounds like it’s still a bad idea unless you know all of the parameters used to generate the keys and can be sure what information is actually encoded in the keys.
Technically neither of these are donations, but:
I subscribe to Firefox VPN, and don’t actually even use it, just because I want to support them in a way where money could possibly towards FF dev and not just the Mozilla foundation (which can’t fun Mozilla corp work AFAIK).
I also have a supporter subscription at https://neocities.org because I support his ideals. Plus I get dirt cheap, easy to use static hosting out of the deal.
Edit: Oh, I guess humble bundle purchases might count, I do at least slide the sliders to make sure the charities get most of the money.
Edit 2: Oh and the Calyx Institute, that’s actually a proper donation to a registered nonprofit. With my $400/year donation I get a 4G hotspot with actually unlimited data. (They also have a $500/year for an unlimited 5G hotspot, I just haven’t felt the need to upgrade since they started offering that.) I also use CalyxOS, so it’s nice to feel like I’m supporting that.
OP is asking about userChrome.css, which applies to the style of the browser window itself, not webpage contents. Websites can't view the markup for the browser window itself (which, fun fact is (mostly?) just HTML too), otherwise this would all be moot and they could just look at your list of tabs or your username in the menus.
I think you might have misunderstood something along the way. You don’t need to use Chrome to use Element. Element is a client for the Matrix federated chat protocol. It exists as a web app (that works just fine with Firefox), an iOS app, and an Android app (that’s available in F-Droid). You can also use any other Matrix client you want.
And if you want to use the same account, the only thing you won’t have access to is your past encrypted messages.
The best way I know of is finding a device that’s supported by gadgetbridge: https://codeberg.org/Freeyourgadget/Gadgetbridge#supported-devices (be sure to check the warnings, some devices require you to pair with the OEM app first or possibly even keep the OEM app around)
Though, I used this with an Amazfit Bip and didn’t find the data particularity insightful. It often was just straight up wrong about whether I was sleeping or not. So, I too am curious to see what other answers come in.
[edit: To be clear, I assume the part that OP is not sure if it’s satire or not is “or switching to a more privacy-conscious browser such as Google Chrome.”] The emphasis in
is in the original. To me that clearly implies that they are of the opinion that in general Google & Chrome are worse on privacy than Mozilla & Firefox. The comment at the end is just tongue in cheek snark alluding to the fact that in this particular case google did better for privacy in Chrome than Mozilla in Firefox.