Definitely agree they should be split up if possible. Octoprint and Home Assistant are both rather demanding on a Pi, particularly the Pi 3B.
I would however opt to run Pi-Hole on the Home Assistant device as there is a plugin built in for it, and Home Assistant is the kind of thing you would be more likely to leave on at all times.
Just as a tangent, definitely get an SSD for whatever device is running HomeAssistant and set it as the boot drive as the constant writes will cause your SD card to explode in a huge fireball after not too long.
Definitely agree they should be split up if possible. Octoprint and Home Assistant are both rather demanding on a Pi, particularly the Pi 3B.
I would however opt to run Pi-Hole on the Home Assistant device as there is a plugin built in for it, and Home Assistant is the kind of thing you would be more likely to leave on at all times.
Just as a tangent, definitely get an SSD for whatever device is running HomeAssistant and set it as the boot drive as the constant writes will cause your SD card to explode in a huge fireball after not too long.