I can't seem to find CCR1009-8G-1S-1S+PC anywhere in Poland. Literally all shops have "out of stock" or "temporarily unavailable" or "ask for availability" status. Is there any external reason for that? Is this product discontinued? Or super ultra popular? Or it's such specific and not popular product that shops don't offer it in mass amounts only available upon order?

Does MTK have any official partner in Poland where this router must be available (in worst case available upon order)?

No problems, but very popular. Demand is very high. It should be arriving in a month or so.

Lol. Is it? I mean i don't know it sounds a bit funny considering at least to me it looks like kind of total overkill home router because in enterprise RM version is probably better choice. So it's a bit surprising that such really specific router is that popular. Maybe because it's one of a kind. I'm planning to get it for home thus high rpm fans are no option but I didn't know there's so many people building 10G home network.

Or am I mistaken and this router has some other than home, really popular use case resulting in such high demand?

Now that 500/500 speeds are becoming more common on fiber-to-the-home, this is about the lowest
model of MikroTIk router that you can deploy to handle the full speed without having to tweak all
performance out of the existing RouterOS. Even the 3011 has difficulty with that.
If it were not for your home use, I would recommend the CCR1009-8G-1S-1S+. Dual (redundant)
power supplies and fans, rack mount with the display on the front. I have one in use at work
(in a noisy patch cabinet) and it is a really nice router. While I was configuring it at my desk, the
noise did not seem that bad, the fan RPM is regulated to keep the CPU temperature at 50degC,
so when it gets air at 20degC the fan does not run that fast.

I have one more question regarding 1009 then. As actual 10G is kind of expensive (I mean NICs) I'll be probably using 4x 1G bonding instead but it's "port expensive" solution. I see that CRS226-24G-2S+IN (I believe demand was really low) is EOL so there are 2 expansion options - RM version (luckily no fans so can be used at home) or CRS210-8G-2S+IN. And VLANs over SFP+ of course.

do you have any experience with performance of such ports "extension" for 1009? I mean - will it actually work more or less as if 1009 had 12x independent 1G ports (plus that 4 port integrated switch)? As in - can CRS210-8G-2S+IN pump 1G (VLAN switching) to all ports simultaneously achieving total 8G and CRS210-8G-2S+IN total uh... <10G on any subset of ports? Lets ignore fact that 1009 probably won't be able to handle 8G routing but lets say 4G or even 3 would be okay.

Or there are some bottlenecks inside one "block" of switch? Because as I see it 1009 has realistically 5 gigabit ports. So if I'd like to connect 2 machines using 2x (4x 1G bonding) I need 8 gigabit ports so the only option seems to be using 4x 1G on router itself and 10G SFP+ and switch capable of pumping 4x 1G as well. I know this math doesn't take real 1009 performance into account but it's quite general example we can take 4 machines 2G bonding each so it'd be the same.

I have no experience with that, in my application I use 5 x 1Gbit port only (port 4-8) and have no need for >1Gbit performance.