I’ve been riding gravel for 2 years now on my aluminum 27.5 XC hardtail. I am using Maxxis Icon 2.3” tires. Although it works fine, I am now shopping for a rigid, drop bar gravel bike as my distances are getting longer, and I need more low gears for speed. I don’t think suspension is necessary, but I would go with wider tires (45-50mm) on 700C wheels as my roads can get quite chunky and loose.