Posting this cause I spent hours looking on Google and asking ChatGPT (which gave the wrong answers):
The supported Samsung dongle (WIS10ABGN) from the manual uses the MediaTek RT3572 chipset.
Just having that chipset doesn't mean a dongle will work, because the driver has to work, too. The hardware could be fully the same but when it connects, the driver gives an identifier; if it's not in the list of compatible identifiers, it probably won't work. If a stick says it's compatible with WIS12ABGNX, as far as I understand it, it becomes much more likely that it'll work, because it has to identify itself to devices that support the WIS10ABGN.
I took a dice roll on one on Amazon and it worked. "Wire Less Network Adapter, Dual Band Wire Less N Adaptor, 300Mbps High Speed 2.4G 5.8G USB WiFiAdapter for Ralink RT3572 Chipset for TVs" which is "PUSOKEI" brand. I see like 6 other ones coming up when I search for RT3572 and they all have the same images. They'll probably all work, but I've only tested this one. I put an image of it below. Note: it's probably 2-3 times larger than you're picturing.
Make sure StageScape shows firmware version ≥1.20 when it starts.
You test whether it works by hitting "i" on the top right, and hitting "Settings". https://line6.com/data/6/0a06434c12bb52431be9dd7c2/application/pdf/StageScape M20d Advanced Guide - English ( Rev D ).pdf#page=82
