Apparently, nothing lights a fire under your butt as trying to take your TV stand apart in order to be able to saw metal easier, only to realize that the metal piece to be sawed is actually attached to a thicker piece of metal that you definitely won't be able to saw, and then putting the whole TV stand back together again and making some calculations about building a side extension to the TV stand from wood and then realizing how much wood sawing the extension would require so you realize that deconstructing the TV stand was actually a step in the right direction because sawing the metal you can't saw was actually the easier path all along.
So, naturally, while the TV stand stands there intact after I put it all back together, I managed to build a hanger for the bird cage and start sawing the IKEA bookcase pieces that need shortening for the bedroom TV cabinet and marked the cut lines for the height extension units in the other bookcase to make room for the ventilation shaft that I cannot move.
Yes. Mildly put, the whole Penthouse renovation saga is turning out a nice piece of entertainment. Not just the TV cabinet, as advertised earlier, although I should mention that after buying 153 degree hinges for the cabinet doors, I found out that those hinges do not fit the indents in the door (how hard would it have been to declare some measurements at least?), so now I have to make new indents with this one special screw I had to buy specifically for this purpose. The good news is that if I manage to screw the whole thing up, the doors might just work with regular 95 degree hinges as well - and those I already have installed and ready to go.
TLDR: Finding out how hard the TV stand solution will be, I found everything else to be a piece of cake in comparison, and now things with the Penthouse are moving a thousand miles per hour.
