This is one of those cascading failure things...
I have a several-years-old AOC 22" tv in my office that HAD a Roku Express + connected. It worked fine until the Roku started having problems (unrelated to Roku but Youtube TV had problems) and had to be replaced with a 4K streaming stick.
This TV has 2 HDMI ports and it doubles as a secondary monitor for my desktop computer.
With the 4K Roku, the remote WILL NOT PAIR with this TV (the music never goes off). Which means no on/off, volume, etc. I took the OLD Express remote and it DID pair with whatever it needed to AND it's been working with the 4K streaming also - so the old Express+ remote works FINE. All would be good EXCEPT the remote is failing - the volume buttons no longer work, the mute is occasional, but everything else is still fine. Mostly it's an annoyance.
I'm thinking about replacing the TV with an inexpensive 22 or 24" monitor with speakers, and using that for the Roku and secondary monitor - there are a lot of inexpensive 22" monitors (or possibly a 24") on Amazon. BUT, now that I've found the Roku remote appears quite limited as far as what devices it will work with, I'm concerned that buying one of these basic monitors like a 24" Sceptre or some other inexpensive unit is going to have the same problem with the remote refusing to pair.
Ideally, I'd PREFER to have a code that WOULD pair the 4K remote with the existing AOC tv, but I haven't found one yet.
So, if I end up replacing the TV with a monitor, am I going to have the same problem with the remote not working? And is there a list somewhere of what TVs and/or monitors it WILL work with?
As you noted, many computer monitors do not have sound, so you have to have some other way to hear your content. But unless the monitor has an audio splitter built in that can take the audio from the HDMI stream and send it to external speakers, you really need the monitor to have its own sound system. Otherwise you have to pull the audio from the HDMI stream with an adapter prior to the TV, and adding adapters just adds a place for errors to occur. Of course, you could put an AVR in the HDMI string and let it handle the audio.
However, I have actually replaced almost all of my computer monitors with HDTVs. Most are Vizio, but I have a Samsung I use as well. That way I have an audio system if needed, and they all have HDMI inputs for connecting devices.
You could just upgrade the Roku to Roku Streambar, which has built-in speakers and Roku streamer all in one chassis. Sound stays with Streambar and video goes to your monitor.
My plan, if I decide it's worthwhile, is to get an inexpensive monitor with built-in speakers.
My much LARGER concern is with the remote and the pairing issues I keep having. Again, my preference would be to have the 4K remote from the streaming stick WORK with the AOC TV. So far that hasn't happened. Since the remote from the Express+ WORKS with the TV, there has to be a code that does, but the 4K remote does not seem to provide that code. I presume an AOC tv is actually somebody else's with a different name slapped on it, but I have no idea what.
But, having had this problem, I don't have much confidence in the Roku 4K remote to work with either inexpensive TVs OR inexpensive monitors.
If you go the monitor route, you will want to make sure the monitor claims to have an IR receiver and features like a volume control for its internal speakers. I think you will find that most monitors have neither.
I wondered about that 'cause I don't recall ever having a monitor remote volume control. May be simpler just to get a small TV if I get to the point where the one I'm using is sufficiently annoying.
Have you tried the Roku remote control phone app? The android version lets me control every roku device with the same app via wifi. It is very useful!