Hi there, welcome to community.
There are couple of ways to do it. Assuming you want it on material level on the mesh object.
1- (As you do ) You can make a RenderTarget, put a WidgetComponent, Take a snapshot etc. Then put the RenderTarget inside the material and it’s done. However this is generally I don’t advice doing, since it’s not necessary if its just Text or Numerals. If there is complex shapes, moving textures then you can prefer.
2- You can take a look at this one, it’s basically a sprite and you change texture UV to match whatever you want to print.
3- If it’s more complex shapes, you want to use RenderTarget to make something more fancy and updates with ease then you can take a look at this one. On step 5 you can simply make an update, render widget to a texture. There are details of update rate etc. in that post entirely.
4- You can actually FontSample in materials so FontSampleNode->BoxMask->UVPanner is similar to 1st but more modern and dynamic.
Let us know.