For Windows I’ve used Game Save Manger for years, since it’ll auto find save locations that you want to select to be backed up.
On Linux you could use a program like Timeshift and specify the general directory your save files are located in and have them backed up on a schedule as well.
As for saves. I’ve had some luck finding them from nexusmods and sometimes steam message boards or guides.
That sounds like what I’m going to end up doing. I wasn’t sure if there was a general well known hub for save files I was unaware of.