It’s nice to have some resolution, but the thing is - even if you have 0.1V/0.01A resolution, you can measure voltage and current with few multimeters, you will never have matching values. If you have a match, it’s not going to hold through the whole range. Some volt/ammeters have trimmers, probably these modular buck converters from RD do too, so you can calibrate a bit, but you’re always going to have some error, and the error will be greater than resolution, even if you spend a fortune on a ps. The thing with adjustable dc power supplies is that you can easily get to some power, you probably have a psu in your pc capable of few 20-30A rails at 12V, and you can buy Zhaoxin kxn3020d for 70 bucks (which I would warmly recommend), prices of ps units start multiplying with all the filters, high quality caps, all those things that lower the ripple as much as possible, then you have multiple outputs which are electrically isolated so you can put them in parallel or series if necessary, than there are fancy options like timers, constant power mode range settings, load settings, intelligent charging, and if you throw some money on top of THAT pile, only then you’ll have a high precision everything through the whole range. This is why there are European power supplies that will cost you 10$/W, and that is why I strongly suggest a kxn3020d if you’re not from a country that will bleed you dry with customs fees like I am.
I had one of these Ruideng units under a scope, I think that it was a DPH version, similar in power, really couldn’t say which one exactly. Anyway, these are great units for the money. Everything except the housing 
Anyway, you don’t have a problem with switch ripple, you have problems with current spikes on (probably only) low load, if I understand correctly from videos. I mean, you have current fluctuations, you shouldn’t have voltage fluctuations in constant current mode? There’s a high frequency ripple, maybe a mV or 2 per W, that’s the way smps works, but you shouldn’t see any power fluctuations, other than ones caused by heating up the led.
I mean - do you? What happens in cc mode, and what happens with a bit more load? Not like induction heating, I mean, what happens if you power several straw leds, in parallel AND in series, have you tried, do the fluctuations persist?
I just assume that the problem is only with current regulation with very low draw load, that’s not to say that this is “ok”, it’s not ok and it should not happen.
