Just feel like chiming in here. I have a Macbook, when I'm working on the couch or whatever, yes the trackpad is great. But most of the time I'm at my desk using an ergonomic keyboard and mouse. I use the Kinesis Advantage keyboard and the Evolent vertical mouse.
I use these to avoid pain in my wrists and fingers so it's very important.
I'm trialing Kagi and Orion, my typical browser is Firefox almost entirely because of this auto-scroll (and better privacy related extensions). My mouse has a mouse wheel but that's it's own sort of painful and I only use it in certain situations. So for me, this is an unfortunate missing feature of Orion.
I have seen that there are some extensions that allow global auto-scrolling in macOS (for example https://smooze.co). Similar to how I've learned that 1password has a universal auto-fill (and as such I don't need the extension in Orion), maybe this is a good solution for me in more cases than just Orion.