Thanks for the reply.
There are likely smaller consulting firms in your area, other than Robert Half, that would be looking for resources. I'd make another run at Robert Half and look at the other firms in the area. In any decent sized city, they exist. As a quieter person who doesn't like putting in the effort to maintain a network, you really need someone that'll do that for you. I don't see introversion/quietness as a job obstacle but it can slow down finding work as an independent consultant.
As for the degree, I wouldn't say that it necessarily has to be a CS degree. But many hiring managers see someone in their 30s who goes back to school and gets a degree as particularly motivated and committed. It opens doors, maybe not everywhere, but more places than you are finding currently. It could be accounting, finance, software engineering, etc. just not a non-applicable degree such as Medieval English Literature. I was in my mid-30s and already a manager before I got my MBA. Why did I do it? Because of a conversation with my boss's boss (yes, we did skip levels even in the 80s, although they were often on the golf course or at the bar) who told me that the lack of a graduate degree would hold back my advancement, not because I didn't already have the knowledge but because I didn't have the credential. Not necessarily "fair" but that's the real world.
Interviewing takes practice. Some recruiting firms offer coaching on interviewing. Many interviewers are simply bad interviewers, trying to hit you with gotcha questions, put you on the defensive, show how smart they are, etc. Personally, I've never been a big fan of any of the behavioral approaches to interviewing. I've had numerous HR managers tell me how effective they are to screen out "bad" candidates. I don't see interviews that intentionally make the candidate uncomfortable as productive. Some hiring managers do. And sadly, one of your obstacles is that far too many companies/interviewers are searching for explicit knowledge instead of talent. That's one of the reasons job ads are so dense with acronyms. I did ask technical questions and did have candidates interviewed by senior technical staff. And I didn't hire anyone that the technical team labeled as unlikely to LEARN (not know) our environment/business.
I interviewed with Microsoft Consulting in the late 90s, when I was a bit older than you, and it was a brutal all day affair with 8-9 different interviewers. Some parts were deeply technical and I did less well, e.g., a deep dive into the MS server security model. Still at the end of the day they made an offer and ultimately I turned it down (how smart was that). I was married, had a house, etc. and the lifestyle changes, e.g., spending the first year living in a hotel in a very small city, just weren't palatable to me.
I've also interviewed with Amazon, in my mid-50s, and it was a totally different experience. Numerous phone interviews, as well as an online test prior to the onsite. A lot of the questions involved thinking through scenarios and how one should approach them. Far less focus on deep technical issues although there was some. It was actually a fun experience but ultimately didn't lead to an offer. It may have but when the hiring manager walked me through the structure of a deal, e.g., the signing bonus and it's vesting schedule, starting salary (much less than I was making), the work expectations, coupled with my prior research into the attrition rate of people in similar roles, it wasn't a smart move for someone in their 50s. Seattle isn't cheap.
The upshot of all of this is that the FAANG environment isn't for everyone for a variety of reasons. There are folks on this board that are/or have carved out successful and satisfying careers in the Big Tech world. Others, such as myself, did very well in the commercial world, e.g., banking, finance, etc. In the commercial domains, at least in most cases, the demand for computer science degrees is lower. We didn't need developers that were experts at writing, for example, recursive descent parsers. We needed developers that understood debits/credits, internal rate of return, etc.
I've been retired for a couple of years. Certainly, my views don't represent the majority here on HN. I carved out a good career in the Fortune 500 and worked on some very high profile projects that would be recognizable here. I had a lot of fun and made enough money to have a decent retirement. Take these as a one man's opinion and think about what you really want out of life. Then work to achieve it. And most importantly, again in my opinion, remember the journey is a process not a destination.