Back in the day I built several pieces of lab equipment requiring a high quality beam from laser diodes. Both focused to a point and expanded to a foot or so diameter with a respectably uniform intensity across the beam.
Starting with professional quality units already fitted with internal polarising filters and beam shaping optics, £1,000 up in the day, a spatial filter before my optics was essential to get any form of acceptable beam or focus quality. A spatial filter for a visible laser is a pinhole around 15 to 25 µm diameter so some pretty effective beam shaping and quality focusing is needed to get most of the laser power through it whilst stripping out the noise.
Even then, whatever you do there will be some speckle effects. Much less than a proper gas laser, which is why we went laser diode, but still there.
The modern cheap import laser diode units perform remarkably well given the price point but, objectively not that good. Given lab facilities I’d like to get my hands on modern high end devices with diffractive or holographic optics inside to see how good they are compared to 2 or 3 decade old school devices.
Clive