newbie to fuji

Once you absorb that, and try some ideas to see if they work for you, it will be time to chat about star trackers and goto mounts. Alt-Az and German Equatorial Mounts! (Remember the bit about joining the local astro club).
oh, there is nothing at all bad about using dedicated astro cameras, they work extremely well and can get you fantastic images if you put the effort into learning how to use them. But they are single purpose dedicated equipment, they do not work so well if you want to grab a camera and photograph kittens and puppies in action or birds in flight.

Hmm, intervalometer: start with the one built-in to your camera; https://fujifilm-dsc.com/en/manual/x-h2s/menu_shooting/shooting_setting/#interval_timer_shooting
scroll down to the interval timer section. One thing to make certain, shoot completely in manual mode, set the shutter speed, f-stop (if you are using a lens) and iso all manually. Turn OFF long exposure noise reduction -- this type of noise reduction can be dealt with in your image editor by taking some blank or "dark" frames (with the lens cap on) right after you you shoot the "light" frames, put all of the dark frames in the editor as layers whose blend mode is set to average or better yet median, merge into a single layer and use as your master dark frame. Put it as a layer on top of the "light" frame and set its blend mode to subtract. Merge the two layers and continue onward in your processing (Uh, this may seem obvious, but also save everything separately as you are working in case you have to start over -- which does happen. Save early, save often). This removes hot or stuck pixels and can remove something called bias noise (if it is there).
Save your money, save your money, save your money. Some folks (without any traces of irony or maybe just a hint of a smile) will tell you astrophotography is a black hole perched over your bank accounts. For every problem you encounter, there is a solution, it costs money, fixes the problem and creates an entirely new problem that has a solution that costs ....
Turn OFF IBIS and OIS, these get in the way.
The section I listed has some advice about tripods and power banks. In the summer time just use the camera's battery, along with a second back-up battery. Use the power bank with the appropriate adapter in the winter time (when the temperatures drop below 60 degrees Fahrenheit (16 degrees Celsius or so). Make sure the batteries are charged before you go out imaging, you should be fine for some few hours.
Depending on your budget, the most important purchase you can invest in is the tripod and mount. Be careful about using low cost tripods or high dollar tripods because a lot of them are built with terrestrial photography in mind. When you are shooting at 1/200 or faster, small little minor vibrations will not affect the image. Shooting at 20 seconds or five minutes or so is a different matter, you may start thinking the vibration from heartbeats is finding their way into your image and smearing things. 😃 Here is one approach: https://www.berlebach.de/en/ (The site is in Germany, the prices are in Euros, replace the comma with a period to get an idea of US versions, i.e. 159,00 ---> 159.00, the prices will need to be converted into US dollars -- it is common outside of the US to use commas the way periods are used in the US.). Carbon fiber tripods can be good, if they are rated to hold 50 lbs. or more (23 kgs. or more) because these begin to be stout enough to absorb the teeny tiny, itsy bitsy vibrations that happen. Uh, remember if other folks are in the apartments or on the ship's deck, there will be vibrations.
Try to have a lot of fun, because it should be fun, and can be very frustrating if you want it that way. The universe wobbles, so does everything in it.
If it is possible, join your local astronomy club. You may be the only one imaging, maybe or maybe not, but you can get the chance to see how the equipment works and find out why. Because you are going to encounter things that will make no sense at all as to why you do that, but you need to do if you want the images.

Thank you so much, Jerry. I am so excited not only that I can use the camera for general photos and video, but also Astro. This has been a great investment for many years to come. I almost wanted to spend money on a dedicated Astro camera, but now I am confident in my purchase. I am planning on going to Mexico on a cruise, and I am intrigued to see if I can do Astro on a cruise ship. I have a balcony to try it out. Do you have any recommendations for a good intervalometer? I did notice that I can not use a 9v power for the x-h2. How do I charge for long exposures should I invest in a power bank?