I went here because I could do a one time donation. I plan to see how things go and eventually set up a recurring one though.
https://opencollective.com/lemmy
I found it on the main lemmy page where you sign up for a server. It probably needs to be posted in more places, like on the communities pages. (there's a patreon site too where you can donate)
I left Digg probably 13 years ago. So I've been a redditor for a long time. It has changed enormously in the last few years though.