Not necessarily. GNOME and KDE dependencies and "base system" for flatpaks to run in are flatpaks themselves so apps that depend on them will not use duplicated dependencies. Storage usage may not be as efficient as using a traditional package manager but you don't install a new OS per app either.
Their product quality and servicing are top notch but they don't have a good price/performance ratio. "Lemur Pro" starts at 1.4k and this gives you Intel GPU & 8GiB RAM. https://system76.com/laptops/lemur#specs
If you have .drv file, put them in /usr/share/cups/drv/. If you have .ppd file, go to http://localhost:631 , choose "printers" from top, add new printer, CUPS will give you the option to supply .ppd file.
Hunting down drivers then manually adding printer via CUPS interface is exactly what I did for my Samsung printer. I had to install "splix" and registered my printer via web. Good luck.
China blocked Flathub