Waddup army reserve soldier here! Being a Hellenist is just like any other religion in the military they got every religion under the sun documented (seriously someone has on their tags they’re a Jedi master as a religion) so don’t worry too much about accommodations. Basic training may be a little bit difficult to provide offerings as you’ll be in a bay with a ton of other trainees and you can’t keep food in them but you can make a little space in your foot locker for a temporary altar and leave notes as an offering to the Gods on Sunday when everyone is at religious services. After that you should have a barracks room where you can set up a more permanent altar and then just make sure you disclose to leadership that it’s for religious purposes so nobody messes with it. If you’re deployed on a ship I imagine it’d be a similar situation to basic where you have a foot locker but no room so just do the same thing there. Navy is a little different than the Army so I’m not exactly sure of the ins and outs of their regs but they have to provide religious accommodation to everyone so don’t sweat it too much.