In my testing on a Kobo Sage, any stylus using the N-Trig/MPP protocol will work. This testing was done about 18 months back when my work was testing various styli as replacements. This does limit you to a stylus that will require a battery or supercapacitor to power it. The screen electronics are less complex which a bonus for those who do not want a stylus. All the MPP 2.00 styli worked in my limited testing though we did not test any of the later MPP 2.5/2.6 styli. The two MPP 1.51. styli we tested did not have pressure sensitivity which might be a deal breaker for some people.
You may want to take a look at
Microsoft Pen Protocol (MPP) Stylus Compendium for a list of manufacturers updated Nov., 2023.