I was into boardgames for most of the 70s, mostly due to my older brother being in a club who's members would get any title reputed to be worth playing - partially aided by a high school's budget. Other than the mainstream boardgames published by Mattel, Milton Bradley, Parker Bros, etc., the only others available were the shiny, new & cool, but affordable wargames like Panzer Blitz and Squad Leader. I don't recall much of anything of those that might be conducive to RPing or might inspire RPG rules. Kingmaker maybe, which came out in 74 and had Players acquiring Nobles which were represented on the board by figurines. Outdoor Survival which also came out in the early 70s, is another one that comes to mind. IIRC it had some play mechanics that were a bit like wilderness adventuring in a hex crawl.
There was also a healthy, expanding tabletop miniatures scene in the 70s. I don't know if that was a continuation of an existing community/hobby, or something new and spurned on by wargames - probably a bit of both. I'm a member or a local tabletop miniatures club that's been running for almost 50 years. A number of our formative and older members attribute the advent of RPGs in the late 70s - early 80s as stealing away a big chunk of their community. So as far as they're concerned, there was a trajectory from tabletop miniatures to TTRPGs for at least the player-audience.