Humble posts?

Not the first, you are right... but currently is the only one even considering to build a phone with slider.

I don't know what technical skills you have, but if you want to build a phone which functions well in every aspects, a slider keyboard makes the whole process much more complicated to do well.

Even the radio frequencies used in old slider phones were much less than this phone is designed to support as a lot of things changed in last years.

So they had to design appropriate antennas, good transmission / reception even in opened and closed state and ensure the phone meets also radiation requirements.
This need a lot of effort and also testing.

Testing does not exactly mean certification. Prior certifications, you have to ensure the phone will be able to pass it, so you have to do similar tests for yourself, maybe do some modifications and test again, and finally do the official test.
Prior tests may not mean worse tests, maybe even done by the same (or similar) test equipment, but unofficial ones with no certification as result, but cheaper for development and you may do minor modifications during the occasion and do additional testings.
These are special and really expensive equipments, so special laboratories and even some universities have them (I am speaking about EMI / EMC measurements and Faraday cage for example).

Doing this for a small company can be really hard and expensive.

...and as they already have FCC regulations passed (which is also really expensive as its own), they really had to do such tests written above, otherwise the chance of having successful FCC certification is extremely low.

It is not really easy to copy the design (if we are not speaking about an exact copy) - so to design a similar phone takes time.
Big manufacturers may be able to design a similar phone in less time, but they are also thinking it twice.
They can sell bunch of phones with much simpler design (practically they look the same anyway), but slider phones are more expensive to manufacture (less profit) and may not would be sold as the same rate or if so, bigger manufacturing price would make them a worse option to manufacture as the less profit.

Otherwise, for F(x)tec, that is why it is a good idea to build a slider phone. As an n'th manufacturer, they would not survive at all - there are several manufacturers.
...but as a manufacturer of a slider phone, they may sell enough devices to gain good profit.

If I will be satisfied with Pro1, I would also buy their next model even if other manufacturers have slider phones. So if their build quality is good, they may have good reputation and also future sales.

Please sit down and wait a few weeks.
You are constantly saying the same and the same negative thoughts without real knowledge on what is in the background and without any knowledge about what things may happen.

For them, the most important thing would be the good reputation, so to be able to sell phones to prove the users this is a working model then there is high chance of having much more orders if everything are right.

So that way you try to decrease their chance regardless of their effort of doing everything right - I understand that can make them angry.

Also, please remember that you said they are liars and scammers without knowing the real situation.

Anyway, you may be right about their communication could be better, they may also have their consequences what to do a bit different if they will build up another product later.

Please stop being negative for a few months and let's back to it when we know the end of the story.
I would like them to build up a high quality, good brand and reputation, so please don't ruin their business.