It makes no sense to not let the site online in an archived form, for the posterity It wouldn't even be a significant cost and ads would recoup it anyway There should be a way to donate a website to the Internet Archive so that they run an online archive on it, basically keeping the site frozen forever (rather than relying on the Wayback Machine which has worse UX)
You can store the resulting WARC file wherever, be it on S3 or under your pillow.
As an archivist, I urge everybody here to not reinvent the wheel, please..
[2] https://en.m.wikipedia.org/wiki/WARC_(file_format)
[3] https://www.iso.org/standard/68004.html
[4] https://www.loc.gov/preservation/digital/formats/fdd/fdd0002...