Since the manga follows the original light novel closely, many readers use the translated novel as a "script" while viewing the high-quality raw art.
To support the creator and get the highest resolution possible, platforms like Comic Walker or Nico Nico Seiga are the primary sources. These sites provide the cleanest "raw" experience without the watermarks often found on pirate sites. oukoku e tsuzuku michi manga raw best
If you’ve found a "best" source for the raws but can't read the dialogue, you aren't alone. Many fans use these methods: Since the manga follows the original light novel