Numbered Universal remotes

Not via preset code, no. UEI made remotes under such brands as One-For-All, Inteset, Insignia, and Onn can be programmed to emit the number keys for Roku devices like the Ultra. But it would only work on the Roku Ch guide or its Live tv channels. It wouldn't work with cable apps like Spectrum, Xfinity or Pluto app. 

To program the UEI universal remote you would have to program in a 5-digit code for each numeral, but only once for each digit. After it would be mapped to a key like any other command. Some of the models include OFA URC-7880:

Amazon.com: One for All URC7880 Universal Smart Remote Control up to 8 Devices with Free Setup App - Easy Learning Feature - Infrared Connectivity Technology and 3 Shortcut App Keys – Black : Electronics

Inteset 4:

Amazon.com: Inteset 4 in 1 Universal Backlit IR Learning Remote for use with Apple TV, Xbox, Roku, Kodi, Nvidia Shield, Most Streamers & Other A/V Devices : Electronics

Insignia NS-RMT3D21:

Insignia™ 3-Device Universal Remote Black NS-RMT3D21 - Best Buy

Or check ebay for Onn 6 universal remote, not the one with purple cursor pad, the white one only:

Onn 6 Universal Remote for sale | eBay

Once you have one of them, the Roku setup code is 3061 or 03061 depending on what model you get. Then to map the 0-9 digits to keys on the remote use these codes:

0- 00101
1- 00230
2- 00232
3- 00228
4- 00235
5- 00231
6- 00233
7- 00100
8- 00106 
9- 00102 

Ch UP- 00183
Ch Down- 00185

1. Roku device with 3061 code programmed to it

2. press and hold SETUP for two blinks, release

3. enter 9 9 4

4. tap SETUP for one blink, release

5. enter five digit code from the above list, like 00101

6. pick a key, like zero

repeat the above steps for each command, using a different 5-digit code in step five, and picking a different key to map to in step six.