Well, you got Deadzone 3rd edition launching the next month
https://www.manticgames.com/games/deadzone/deadzone-3-0-two-player-starter-set/ and Bot War
https://tradersgalaxy.com.au/learn-about-the-bot-war-factions/, but i know nothing realy of these game to say if they fit your goals other than they are sci-fi and skirmish. Deadzone is grid movment though.
You allso have
GWs aeronotica imperialis, but the game is very simplified, very expensive and lacking product support, but it is hex bases and movment grid.
(in terms of army i know only of one that has grid movment system and that is Dust1947, wierd world war 2.( mechs,alien tech,zombies,lovecraft in a good old 1947 setting)
1p starterboxes is basicly skirmish content, 1 hero, 1 squad, 1 mech, and the 1p boxes are fairly balanced even if the points value do not reflect that. Only downside to this game is they are remaking the models in better quality, so product avalibility is an issue.