Found a bug when changing my wifi password and thought I'd post it here for visibility / if others are having the same problem.
When I changed my wifi password, I went to turn on my roku, which turned on fine saying internet not connected, expected. However the remote was working very intermittently, every 1-2+ minutes I could enter input for like 2-3 seconds. During this time power and volume worked the entire time, which have been linked to the TV so I was able to rule out batteries (also changed batteries to be sure).
Reset the roku several times, repaired the remote several times, same issue. Finally I just bit the bullet and spent the 30 minutes it took to enter my password in the intermittent intervals where the remote worked. The SECOND the roku was connected to wireless again, the remote functioned perfectly and has not had issues since.
I assume there is some process either spin retrying to connect on roku, preventing the input from remote, or some process for some reason requires internet to properly receive input from the roku.
Either way, from a long period of testing and turmoil it appears that the issue is mostly definitely linked to the loss of the internet connection. (Specifically through a changed password, though I don't want to go through testing this in other methods).