If you want to help fund Firefox, you can for now just pay for a product https://www.mozilla.org/en-US/products/ and not use it (if you live in a country Mozilla accepts money from). Be vocal about it that you do this to support Firefox (e.g. reply in the discourse thread). I personally recommend leveraging MDN for this as it's right now the closest to Firefox, as in it's part of the Firefox organization within Mozilla. I would hope down the road we could just directly for Firefox, but we need to put money where our mouth is.
Ubuntu only supports S0i3 (modern standby) not the normal S3 sleep. S0i3 has some problems like peripheral not working after resume and higher battery drain during "sleep".