I’ve come to the conclusion that nextcloud is probably the best single Google replacement. “Old hardware” is a pretty broad definition, as I’ve still got Zip disks kicking around. But more than likely, you can run Nextcloud AIO reasonably well. The more RAM the better for sure. But you do get an online office, document storage and sharing, calendar, contacts, tasks (to replace Google Keep), text and video chat, picture storage, etc. Doing all of that really well can take a beefier machine, but keep things in perspective, be patient and you can at least get it going to see if you want to expand in the future.
My preference is paying for Unraid and using spaceinvaderone’s Nextcloud AIO package and accompanying video tutorial is the way to go. Unraid isn’t free, but I highly, highly recommend paying for it as a platform. I feel like it still allows some challenges in getting things set up but in a more fun way to reduce frustrations. And Unraid just does so much.
https://jellyfin.org/