I found some old photo albums and slides (mostly dating back to '80) and I’m considering digitalizing some of them.
How would you proceed in my shoes?
I have a decent mirrorless camera (plus minimal editing skills) and an office scanner, but I’m open to buy extra equipment. I’m also open to sending the lot to some third party studio that specializes in the task, but if possible (and if it’s not much more costly) I would prefer to DYI and process the photos/slides as I review them.

Indeed, an important question, and also, how consistent in sizes, and for that matter, how good a reproduction is wanted.
Things like the Epson FF-680W exist for this sort of task - not terribly fast (and there are believable tales of streaking), but still a whole lot faster than manual scanning, and becomes cheaper than professional services at useful numbers of photos.