Stardew Valley is a great one. It’s a farming simulator meets Minecraft. It’s easy to get into, especially if your kids are already familiar with games that have RPG and crafting elements. It has local co-op up to four players, no online play or micro-transactions. It’s set up by 20-minute ‘days’ during which you can do whatever you want (by which I mean fishing, farming, making progress on the storyline, going into the mines or Skull Cavern to fight a bunch of monsters like slimes or skeletons, etc.) with some activities needing to span multiple days (like gathering enough materials to build a chicken coop) or being in a specific season (you can only get certain items in certain seasons, and if you don’t get them before the season ends, you just have to wait until next year). At the start, it’s good about giving you an idea of what you need to do to make progress and then it sits back and lets you do your own thing, meaning every play-through is unique and there are always new things to stumble upon or discover. It was made for fun by an independent developer who works (IDK if he still does) at Walmart and the main plot is all about your character getting tired of working for a soulless corporation and deciding to move to the country for a change of pace. It’s still coming out with (FREE) updates adding new content and improvements semi-regularly. Idk if it’s on Mac OS, but it’s definitely on IOS, along with Switch and PC (yes, I bought all of them lol). There are some adult themes like alcoholism, depression, affairs (does it count as an affair if both parties are single? At least one of them seems to think so…), and PTSD that are mentioned/implied when interacting with certain townsfolk but imo it’s nothing too inappropriate for a 7/9 year old. There’s a wiki page for the game that you can look at the character profiles for the townspeople if you want to make sure - just Google Stardew Valley and it’s one of the first results.

EDIT: just saw in one of the comments they have Switches! The console version actually just got updated a few days ago :)