I'm an active duty RN in the Navy, current job is a student for another 2.25 years.
All 3 branches have recently cut their nurse corps due to military medicine wide cuts. That is not to say that the military is not recruiting, always upward mobility, as my senior folks are required to retire if they do not pick up a rank, mandatory age retirement, or max time in service for rank.
The military needs OR, CRNA, ICU/ER, APRNs, and med-surg nurses that are deployable. Expect to deploy at least once every 3 years(per duty station) for at least 6-9 months, unless the President pulls us out of these conflicts.
Regarding rank, if your goal is to retire (20 years of service), starting out at the lowest rank (ensign) will be beneficial, and provide 4 years till the rank of Lieutenant for you to learn the ropes. The military credits 2 years for a masters degree, 4 years of a DNP/PhD, and time of experience with a BSN or higher divided by 2. So if you have 10 years of experience would be credited with 5 years of service for rank only (does not count toward pay or toward retirement). With that being said, higher rank = higher pay, but also greater responsibility which you will be evaluated on for promotion. If you come in as a Lieutenant, you will be graded against others who know how the military system works and what is expected, what to do to earn higher marks and such. Which is why I would recommend starting as an Ensign first (not much is expected of you at this point, but to focus on clinical skills. At the rank of Lieutenant, you are expected to start doing administration roles, such as DIVO "nurse manager", and doing collaterals (teaching ACLS, BLS, etc, infection control tracking, and such).
Right now the current duty stations for the Navy in Bethesda, MD; Portsmouth, VA; San Diego, CA; Jacksonville, FL; Camp Pendleton, CA; Camp Lejune, NC; Bremerton, WA; Okinawa Japan; Yokuska Japan; Guam, USA; Naples Italy; Sigonella Italy; Bahrain; Rota Spain. Not an inclusive list, but the ability to go to each one is dependent on open billets and need for your billet (job). To make matters more confusing, all of the East coast this year is falling under the Defense Health Association (DHA), West coast 2020, and world 2021. What does that mean for Navy? I don't fully know yet, but it seems that each hospital will be tri-service, though for deployments you will be utilized by individual branches.
If your goal is to go into anaesthesia, nurse practitioner, or clinical nurse specialist, the military will pay full salary and benefits to be a student for 3 years (can apply at the end of your second duty station or ~6 years from entry).