I’m seeking advice on how to best prepare a strong packet for the Navy Reserve ODS, w/ specifics to Supply Corps. Can anyone suggest advice?

Make sure you're talking to a Staff Corps Accessions officer and NOT a general recruiter. For Reserves, this is typically a capped O-4 FTS (full time support type). Your package needs to pass the sniff test with this one. The screening is so the AO can determine if you're good enough not to waste a senior officer's time (usually O-5/6 with prior Command tours). That's what I did for years for graduating engineers who wanted to go the CEC route (AD and Reserves). I had a long term working relationship with a couple of AOs. In general, they knew to screen out those who can't write and had poor communications skills otherwise. So what does a Reviewing Officer (RO) like me look for? Bottom line, the answer to one question. Is this person worth the investment and has high odds of doing well? We're dropping a chunk of change on newbies and it isn't an entitlement by a long shot. The RO is looking for your personal qualities that say the investment will be worth it. Work ethic. Team orientation. Focus. Fairness. People skills. You're not there to impress. You're there to demonstrate. Good ROs quickly get a feel for your strengths and weaknesses. Don't worry, everybody is human and not perfect. Even so, ROs really want success because they've been around a few disasters when they were moving up. I don't know what the "pass rate" is nowadays, but around 60-70% should be common unless there are few slots to fill and numerous candidates.

Even though this is active duty it might give you some ideas of areas to concentrate on.
https://www.navycs.com/officer/supplyofficer.html