Welcome!
I love the idea of selling your primary and house hacking a 2-4 unit multi. If you are willing to go through the process of living like that you can make massive steps forward with relative ease and simplicity. Say you do something as simple as house hack just one three-plex for each of the next 5 years... you could buy a primary residence at that point and end up with 15 doors! That puts you well on your way to financial freedom.
I am flipping houses for cash flow to invest into rentals, but I am not in a position to house hack. If you like your W2, just do the house hack method for 5-10 years and you can be free. Flipping is not necessary, but could used to expedite your timeline. I have used my HELOC a ton. It can be a great tool, but just make sure you are using it carefully so you don't get in financial trouble. It is not free money, but a tool to leverage you forward.
I like out of state investing for the prices, but generally would much rather have local properties. I am in Lake Stevens and it's getting pretty pricey up here, yet still much lower than in Seattle. "Generally" I don't think the market matter too much, it's all about the overall deal. You can buy stuff out of state for much less, but the earnings are generally much less as well so it's a give and take. Personally I would rather have twice the units out of state that have growth potential, but that's because it it much harder to buy into King/Snohomish County.
If you think about your overall goals for you and your family, that can help you decide your path. Flipping is a different path than wholesaling, which is also different than rentals. You CAN do them all, but they are each a different animal. Always the best option is to focus on one until it gets momentum. If you like flipping, go for it. But if it's only a tool for rentals, then skip it and just focus on methods to get rentals.
REMEMBER... this is a marathon not a sprint. Make a little progress every year and you'll be well set in 10+ years.
I am in Lake Stevens so feel free to reach out.