I agree that Google is rather indispensable. (They should prolly teach search engines in every school.) But it's got its disadvantages and I think best works when you need some specific knowledge, or are very new to some subject and/or get very lucky

As to nozzle availability, you can search "3d printer nozzle upgrade diameter" in 3 minutes, and then start filtering the results. There will be many that are just irrelevant, some which look interesting but turn out to be very unhelpful when you read them, some articles you need to read but probably learn little of the actual search subject while picking up a small bunch of related knowledge. Here's a pretty good one on nozzle diameter selection and speed:

https://craftunique.com/forums/view-thread/1254

But actually it discusses just one printer though some of the observations of course must apply universally. From the titles you may conclude that yes, there is availability of different nozzle sizes but since it's almost always for a specific printer, you're not quite sure if it's 10% or 80% of the market since there are hundreds (thousands?) of different printers. Then there's also the outdated ones from 2013 or so. All of it takes easily a few hours and still I end up with some unread articles cluttering my browser.

One article states about nozzle size and speed:

[COLOR=rgba(90, 90, 90, 0.901961)]After installing the 0.8mm filament, we’ve been able to push this up to [/COLOR][COLOR=rgba(90, 90, 90, 0.901961)]20mm^3/s[/COLOR][COLOR=rgba(90, 90, 90, 0.901961)] and potentially higher by printing at 0.5mm layer height at 50mm/s. On a practical level, this means that we can now print a low resolution version of this cute octopus model in 27 minutes instead of the 3 hours estimated under our previous settings. Printing with substantially higher layer height required that we recalibrate the bed to a somewhat farther distance, but was otherwise very straightforward. The filament used here is Colorfabb Leaf Green PLA/PHA, which we’ve had very good luck with.[/COLOR]
It took me maybe 30 minutes to write my message, but I was also replying to earlier comments and observations and asked several questions instead of just one. (Then I went to sleep and when I came back there was a reply already.) Reading your answer took about 3 minutes and it directly answered a few of my questions and at least pointed out what I'll find when I actually do a more detailed search with Google or whatnot. Your answer will benefit not just me but potentially hundreds (if not more) people reading the forum or using search engines.

For fine print models I meant stuff like this from Ultimaker 2:

https://3dhubs.s3-eu-west-1.amazonaw...er%202%204.JPG

The thread is hardly visible at all - a far cry from what I created with the Ultimaker original (and 200 layer).