There's nothing special about the Roku HDMI extension, it's just a short (4 inches or so) HDMI cord with an HDMI plug at one end and an HDMI socket at the other. I use one several feet long to locate my Streaming Stick in an equipment closet on the other side of the wall from my TV. You may be able to find an HDMI extension locally or online and not have to wait for Roku to ship it to you.
Roku Community Streaming Expert I am not a Roku employee, only a user like you. Please, no support questions via private message -- post them publicly to the Community where others may benefit as well. If this post solves your problem please help others find this answer by clicking " Accept as Solution.".
Streaming Stick 4K+ 3821 | Streaming Stick+ 3810 | TCL Roku TV 43S245/C107X