If your location has no wifi you'd be out if luck even if you had your remote handy because Roku stick products only connect to the internet via wifi. So even if you could control your Roku you couldn't get any channels.
There may be a way if you have all the following:
a cell phone connection with good download speed and that has a wifi hotspot feature
a second device running the Roku remote app
knowledge of the network name (SSID) and password for your home network.
Set up the phone's wifi hotspot to use the same SSID and password as the home network for which your Roku is configured.
Now power up your Roku stick. When it's finished starting up it should connect to the internet and link to your Roku account through your phone's hotspot, but you won't be able to control it yet.
Connect your second device to your hotspot. You should now be able to use the Roku app on this device to control your Roku.
All the programs you view will be coming through your cell phone so you may be limited by the quality of your phone connection, and you'll be limited by any data caps on your account.
Roku Community Streaming Expert I am not a Roku employee, only a user like you. Streaming Stick 4K+ 3821 | Streaming Stick+ 3810 | TCL Roku TV 43S245/C107X | Streaming Stick 3600
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I've given it a try and sadly it doesn't seem to have connected to my mobile hotspot as the second device with Roku cannot see it having followed your instructions.
I did hit the reset button on the device yesterday and the "pair your remote" screen is visible on the tv that the stick is connected to. I'm guessing this stage needs to complete prior it connecting to the Internet.