We've been doing store-bought gnocchi as well, just because it's really easy to pair up with frozen veggies for a meal in less than 15 minutes, start to finish.
For a really simple 'sauce' that'll work with just about anything that needs some flavor - Melt about one or two tablespoons of butter, on low heat, making sure to move it around the pan constantly so it doesn't burn. Throw in three to five cloves of minced garlic, and get it coated in the butter. The heat from the butter alone should be enough to make it aromatic and tasty. We use it on the gnocchi, but you can add it to just about anything "plain" in the last minute to add flavor.
Along those lines - If you have an air fryer or an oven, that plus a digital thermometer can make meal prep really easy. A probe digital thermometer is probably the best $20 you can spend on a kitchen gadget, since almost every recipe I've found on the Internet or in older cookbooks, the cook time can be really sensitive based on the oven used.
More in the "variety" than simplicity category, but still... If a recipe calls for rice as a component at the end or for balancing purposes, you can try quinoa or couscous instead. For plenty of recipes, they'll work just as well.