Firstly, well done on self funding via savings, that’s not easy and it’s commitment.
No advantage doing a diploma, probably one of the biggest time wasters known to man. Nobody cares. I worked in recruitment in a previous employer, and it didn’t contribute to the decision making.
First job will be as challenging as you decide to make it. Some sit at home and email out resumes and wonder why they don’t get employed, some do the tour of employers but have the same Diamond diploma as the other few hundred. Instructor ratings these days are expensive, but I believe it will somewhat be a less bumpy way to enter the industry. I built up a profile at my training outfit (many many years ago) and was talking about an instructor rating well before I finished my CPL. I built up the relationship in a way that I had a job instructing before I even finished the CPL. You will probably need to move to Australia, we have taken on some Kiwi pilots recently who came over to Oz to start instructing, I’d probably to a rating over this way with a place that might hire you if you intend to go down that path.
Don’t worry about the airlines. Too many people get focused on that from the start. We have taken on many new hires recently, I think some of the lower experienced was about 5/6 years in GA.