No, Roku's the competition, just like a Directv remote wouldn't have Dish Network codes either. The Roku soundbar volume commands aren't Audio nor Tv device volumes, which are the only type of codes in the directv remote. What they're is Streamer cec commands.
You could go with universal remote, a very cheap one:
onn. R113663 6-Device Universal Remote - Walmart.com
The directv code is 1377, Roku 3061, the volume commands won't be preset you'll have to add them individually with advanced codes. Which are 5 digit codes for individual functions.
tv power- 00147
volume up- 00134
volume down- 00136
To map to keys on the Onn 6 remote:
1. stream programmed with code 3061
2. press and hold SETUP for two blinks, release
3. enter 9 9 4
4. tap SETUP for one blink
5. enter 5 digit code
6. pick a key
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