24yo with multiple part time jobs supported by family, how should I save while costs are still low?

I'm a 24 year old working multiple part time jobs while I search for something stable based on my degree. One of these jobs that I just started is with a big retailer that offers a 401k but no matching until I've been working with them for a certain period of time. Another is self-employed contracting, which is very on or off. It's not enough to support me living independently in my VHCOL area, but right now I am staying with my family and don't have to pay costs for rent, food, utilities, or a car. I have 6 months of savings in a HYSA and just started a Roth IRA this year.

To sum up, I have both a low, unstable income right now and low costs, which has let me start saving up. I want to get to a point where I can comfortably move out from my family once I am more solidly employed. Given all of that, what should my next steps be? Put money into the retail 401k even though I don't know how long I'll stay with them? Get a solo 401k?

(My degree is in a field that's been very competitive lately, design, so I don't know how long it will take to get hired for something full time in that. My family will likely provide financial support in getting educated in something else, but doing that is essentially a bet that it'll take less time to gain employable skills in another field than to find a job in design. I'm still thinking over that decision.}