Interesting cabinet/case projects

Yes, you can remove the cast iron harp, but you will almost certainly destroy the soundboard in the process.  Since this person's diy project was to use the soundboard for a transducer, I would assume that's why they kept the harp (plus for looks too).

And I agree, there are many other ways of mounting the screen, including a VESA-style bracket directly onto an upright's music stand, but I found with my own customized upright--years ago--that if you're playing virtuostic repertory, you can run your hands into anything that extends the music stand too far out above the keys.  (And I can confirm that it hurts!)  I prefer that grands don't have anything above the key tops at all.

Also, while PTQ has this built-in (and is therefore good for the Resonance Piano which lacks strings), keeping the strings will allow sympathetic resonance, even if they're in poor condition or out-of-tune.  (The resonance won't be flawless in a poorly-maintained instrument, but it will still be there.)  Because of that, you're probably better off getting a poor condition parlor grand for $2-7K and retrofitting it with a transducer system, instead of getting the Resonance Piano for ~$16-18K.  Particularly as it's easy to remove an action from a grand entirely while keeping harp, strings, soundboard, and bridge untouched.  (Yes you can do the exact same thing with an upright, but it's trickier--especially on older uprights--and you don't get as much space savings for a digital to slide into place.)  So I'm not sold on the Resonance Piano itself--particularly as I don't see the point of the two soundboards, it's a good reminder that the Steingraeber/PTQ-style of transducer in a real piano can work extremely well at a somewhat affordable price-point particularly for diy.

It's hard to say with COVID what borders are and are not open and to what kind of traffic.  Shipping agents, shipping agencies, and freight companies will almost certainly continue services even through a pandemic, but ordering any service at the moment could encounter delays or service changes as international situations fluctuating constantly and sadly not for the better in many instances.  I don't know if eastern European borders would be open to someone renting their own truck or not.  (I'm having a hard enough time keeping up with daily travel changes/restrictions within the United States and I don't even travel!)  You'd definitely want to research your options and move quickly before situations change, because any delay could mean that it only ships--either by you renting a truck or by hiring a service--in the Autumn or early Winter.

Those question aside, the most important rule for shipping a piano is to have it crated properly for transport, handled properly, and installed/placed properly.  Moving my GP-300 by myself from the dealer to my upstairs home studio--only 40km--was a significant challenge at each step, and it's a small fraction of the weight and delicacy of any grand piano.  I would recommend looking for a Czech-area piano moving company that do international delivery and have a good reputation among your local piano dealers, as that would likely be your best bet for getting good service and a good rate for this particular move.

Also, it's extremely important to try a piano before you ship it and get to know it very well before having it moved by anybody, and to look at insurance or other protections that the move may involve.  Not knowing if this purchase is through a dealer or a private client, dealers will often have connections to good delivery/moving companies which is a good place to start since they will have worked regularly with any companies they partner with.

While pianos are very delicate, they're also quite sturdy (anything that heavy has to be!).  After any move, you should expect to have a good piano technician do quite a bit of work on an instrument--you'll likely need it anyway to adjust voicing on a new or used piano.  The conditions of a move and a new home (with new temperatures, humidity, sunlight, etc.) will alter tuning, voicing, regulation extensively.  While pianos are delicate, a lot of damage has to happen in shipping for a rebuild to be required, but even the most careful or professional move will result in the need for a technician to do quite a few hours of work (a lot more than just a regular tuning or even pitch raise).

With Pianoteq, what would be the appropriate microphone setting / positioning for this type of equipment?

I did not understand. In what sense do you say that "the Steingraeber / PTQ project is extremely similar to some of these designs / ideas"?