How many buttons do you need on the remote? There are some devices listed in the following:
[2021] Battery Power Switches and Buttons [NEEDS UPDATING]
Otherwise a lot of people just use an inexpensive no contract android phone just running on Wi-Fi. You can usually get one for less than $30 and then you can put either the smartthings app or a third party app something like action tiles or Sharptools on it.
