I second the advice to take a break, as soon as you feel uncomfortable. Step by step you’ll be able to handle more time in VR, but never push it too far. I have a friend who developed a “Pavlov” reflex after pushing too much, that mean just seeing the headset make it dizzy and he had to give-up VR. I made the mistake when I first had my first headset : 2 hours inside it. it took me 2 days before I can try it again. Jut use it for short time, like 10/15minutes, and take a rest. If you feel good, you can play longer.
Also, yes, your machine will have difficulty to handle the G2 at full resolution. In fact, none existing powerful machine can really handle MSFS with a G2 at full render and at headset native frame per second (AFAIK). You need to lower your expectation if you keep the same machine, or really lower the render scale in your G2 to get something acceptable. In other side, other sim/apps/games can possibly give you the max quality result and you could enjoy the G2 on other things (like watching a movie in a virtual giant theater, priceless, or Sim much less demanding like Aerofly FS2, or Simracing if you are into it).
I have an i7 10700K OC, 32GB and RTX 3070 and with low/medium settings but texture ULTRA I can manage 45fps with MSFS in my oculus Rift CV1, which is far lower resolution than the G2 and run at 90Hz usually with other Sims/games/apps.
VR is not also really plug and play, you will have to put your hand under the hood to get the most of it. it’s where such forum and great members may help a lot.