Yep. It's a homebuilt. Surely not pressurised. O2 units available if needed.
As mentioned above, it cruises at around 200 Kt.
Its engine weighs 20 kilos; smaller than an airliner's APU.
Some interesting facts, for anyone interested, in this "Experimenter" article (from some years back, about a prototype of the single seater).
https://www.sonexaircraft.com/wp-content/uploads/2018/01/EAASA_SubSonex_Sept_2016.pdf
EXCERPTS:
"BOB CARLTON COMES SCREAMING down the air show line at nearly 300 mph. The high pitch of the tiny PBS TJ100 jet engine, combined with the vivid canary yellow paint scheme, make the entrance of the JSX-2 SubSonex very hard to ignore ... The JSX-2 could easily be the everyman’s jet, and I was lucky enough to learn why in the most fun way possible—through firsthand experience studying and flying it.
SPIRITED PERFORMANCE The density altitude is a whopping 7,000 feet at the runway. While the takeoff roll of the SubSonex is correspondingly long, that is immediately forgotten as the tiny landing gear break free from the runway surface. Even at this altitude, the JSX-2’s performance is so far removed from most aircraft in this weight class that I can’t help but smile. I quickly get back to business and retract the gear as the airspeed rapidly accelerates toward the maximum gear speed of 125 mph. The gear stows within seconds, and 500 feet AGL passes as I reduce the thrust to climb power (98 percent) and arm the engine’s automatic protection computer (more on that later). Climbing at 150 to 160 indicated, I reach maneuvering altitude after only three climbing legs around the airport’s perimeter. The altimeter now reads 9,500 feet MSL (density altitude of around 10,500 feet), but I’m only 3,000 or so feet above New Mexico’s high desert terrain. As I level off, I wonder to myself what the SubSonex’s performance must be like when operating out of Sonex’s home airport of Oshkosh, Wisconsin, in the dead of winter. I’m sure what I just experienced would seem positively anemic in comparison.
MICROSTEPS TO MICROJETS Tiny jets have been around for decades. In fact, a fascinating array of them have popped up at AirVenture over the years. However, until recently, flying examples have been essentially limited to novelty air show acts and one-off aircraft originally designed with piston powerplants. The jet engines they used were mostly converted auxiliary power units (APUs) or upscaled RC model aircraft engines. While the former suffered from poor power-to-weight ratios and high fuel consumption, the latter lacked reliability and operational convenience. Additionally, with airframes initially designed without consideration of turbine power, the systems, aerodynamics, and performance limitations can easily negate any advantages that a jet engine (of any variety) might offer. Thus, the microjet that offered any real level of practicality remained elusive. Then, in 2008, a Czech company with decades of experience building military-grade APUs introduced something different, something game-changing. The PBS TJ100 turbojet engine was a modern, clean-sheet design with exceptional thrust-to-weight ratio and fuel economy. Unlike earlier microjet engines, it incorporated computerized digital control, an integrated starter/ generator, recirculating lubrication, and spark ignition. All of which contributed to ease of operation, along with reliable and predictable performance. People noticed. Soon, the TJ100 became very desirable for both small manned aircraft and drone applications. Previously built microjets that struggled with engine reliability for years quietly began to convert to PBS engines. While other applications that had been waiting for just such an engine began to move beyond imaginations and into reality
Sonex Aircraft founder and legendary sport plane designer John Monnett set about designing a completely new Sonex. His design would revolve around PBS turbojet power and be optimized to take full advantage of it."