Pressurized aircraft use oxygen only for back up. You can breath because the aircraft adds pressure to the cabin to decrease the effective altitude.
Is this your first plane? Are you going to be the pilot?
Insurance companies smartly require a lot of experience before allowing owners to insure pressurized aircraft. There are lots more things that can go wrong, and at the higher altitude, they become drastic much more quickly.
If you want to be where there is less traffic, and have more cabin comfort, just get a nice single with built in oxygen. There is less traffic between 12,000 and 18,000 than anywhere else, and your passengers don’t have to use the oxygen if they don’t want to. Most people are fine at 16,000 feet and below with an occasional puff of oxygen to clear the head (passengers of course, pilots should consider using ox even lower than required). Get them an ox conserving mask that they can wear or hold up as desired.
I will start another thread that you might be interested in.