This fits
ErGear Dual Monitor Mount Arm 22-34 Inch, Adjustable Gas Spring Monitor Desk Mount Stand, VESA Mount 75/100mm with C Clamp, Grommet Mounting for Most Flat Curved Monitors, Hold up to 26.5lbs https://www.amazon.com/dp/B08BHJP422/ref=cm_sw_r_cp_api_glt_fabc_GZ8Q3H35BDKQ3W8B5GMX?_encoding=UTF8&psc=1
Be prepared that unless you're putting your ultrawide (that's the bottom monitor, right?) Really close to the desk, you're not going to be able to see the bottom of your 27" monitor on top if it's behind the ultrawide.
I'm having the same issue now with my ErGear. This one.
I'm still looking for a pole that I can swap out so I can raise my monitors. The Vivo 39" is the PERFECT pole height for this, but I'm hesitating as I have no idea if it'll fit the ErGear arms. Will let you know if I decide to risk it all lol
Oops, I’m sorry! This is the monitor mount here: