Don’t know what’s your definition of “combat roles” are, but below is the US military definition of Combat Arms.
In the U.S. Army, the following branches were traditionally classified from 1968 until 2001 as the combat arms:
Infantry (1775)
Field Artillery (Artillery 1775/ Re-designated Field Artillery 1968)
Air Defense Artillery (Created 1968)
Armor including Armored Cavalry, Light Cavalry, and formerly, Air Cavalry (Cavalry 1776/ Re-designated Armor 1950)
Since 2001, U.S. Army doctrine has included combat aviation, special operations, and combat engineer forces into the combat arms classification.
United States Marine Corps doctrine designates only Infantry forces as Combat Arms, with all other Ground Combat Element forces (Field Artillery, Assault Amphibian, Combat Engineer, Light Armored Reconnaissance, Reconnaissance, and Tank) considered Combat Support. Air Defense, as a part of Marine Aviation, is contained within the Aviation Combat Element.
You can put multiple accounts on the same device. My wife and I share one switch.
We used to have one per person, but I don’t play as much and we hardly play at the same time so I sold my other switch.
Physical games are sharable but it also means you can only play one device per cartridge at one time. So with games with only 1 save slot, you should get more physical cartridges.
Digital games are locked to the account that bought it. Anyone can play it, but if it has one save slot, then that will be the biggest issue.