As far as I know, an OTG cable is used to convince a normally slave device such as a phone to be the host/master device. I don't think any Rokus are slave devices to begin with so that doesn't seem to apply to them.
Well, you seem to have some interesting product requirements. When that's the case, it's usually quickest to do some reading first. On the other hand, the Roku Express does more than I need it to do so I'm happy with that. The Nvidia Shield is often recommended for high-end users, and a computer may be better still in some cases.
It's not like there is readily available information about this deficiency out there. So how would a potential buyer discover this? They wouldn't. They would presume that a competitive product would, at the very least, be able to do the same as the other products it is competing against in the market place.
Which it should do.
But fails to.
So this forum post may well become the reference point that: the Roku Premiere does not support OTG and is therefore unable to support any external media devices. It is advisable to rather purchase a Firestick, at the same price point, which can.
Well it only took me a couple of seconds to find the link that I gave you above. When a company has multiple models, they probably have different features. I don't believe any one of them requires an OTG cable. Those that say they support USB media just allow you to plug it in directly. There are also media players that have the "deficiency" of not streaming over the internet - but that's what some people want too. There are also TVs and "Smart" TVs and "Smart" TVs have different OS's, features, content providers etc. Even not "Smart" TVs have different features.
At my ISP's support forum, there have been threads pinned to the top for years where people complain about the data cap. And people routinely appear on the forum and say they had no idea there was a data cap. Well... it's not like they're actually hiding it.
If you have questions, and can't find an answer, you can ask. Besides this forum, there are other forums about Roku specifically, streaming, and audio/video in general.
The link offers no specific information regarding OTG or media playback. So it is erroneous.
As for asking questions... I posted this question BECAUSE I couldn't get it answered anywhere else.
Now that it is clear that: Roku DOES NOT WORK WITH OTG and only the units with DEDICATED USB ports seem to allow for media playback from storage devices - maybe someone else asking the question: "does Roku support external devices" can save themselves the expense of finding out and benefit from the knowledge that competitors offer better, more flexible options, for the same money.
That is bound to be useful to someone out there trying to decide on what device to purchase. In my direct "apples for apples" comparison, I say: Firestick.
Local playback via: For the premier: Nothing. For the Ultra: USB.
I don't do local playback on any streaming device (I do have other media devices that can do that) and I don't have a Roku Ultra. I've heard of OTG but never used it on any device. It just searched for: roku feature comparison, clicked on the link that popped up and told you what it said. If you think it doesn't say that, then you shouldn't be listening to me because I'm only relaying it.
The great thing about streaming devices, is they are so small and so cheap you can have a bunch of them. My $30 Roku Express sits on top of my $900 blu-ray player and the Roku gets a lot more use!