And as cliched as it sounds, as a fairly targeted, short-term thing, you might consider jumping on leetcode and grind through some of the exercises there. How useful that would be depends a lot on the nature of the company(s) you wind up interviewing with, of course. Some companies are really big on these kinds of exercises, others less so.
Also, depending on what language(s) you currently know and work with, you might find value in spending some time learning another "trendy" language. Given the next 3 months to work on it, you could probably make real progress on learning a given language to a usable level. For example, if you don't use Go today, maybe spend some time learning it, since it's very popular and seen as "modern" and "trendy".
Or if not a whole new language, maybe just a "trendy" library/framework (for example, React if you're a Javascript person, but don't currently do React).
(Note: Go and React are just examples I picked to make a point. Please don't take this as saying specifically "learn Go" or "learn React".)
[1]: https://www.amazon.com/Cracking-Coding-Interview-Programming...
Two years ago, I ran out of money. So, I started interviewing. One example was interviewing for the Apple Watch team. My experience included the design and code lead of an Apple Watch product, which was featured by Apple. But, I failed the Coderpad. Why? The interviewer wanted me to use a new Swift generic syntax, which I had never seen before. With an unfamiliar code editor. In under 10 minutes. Did it matter that I had an Apple Watch product, which he could download from the AppStore and ran super fast on a Series 0? Nope. Did it matter that he could download a 29K Swift based functional ontology that I wrote? Nope.
The point is that there are two skills: writing code and getting past the interview. The latter is often conducted by a 20-something, just out of college. So, there is more emphasis on tacit knowledge of the tools and techniques. It feels more like passing a finals exam.
A few years ago my CEO hired Gayle Laakman to prep the team for an acquisition by a FAANG. I loved the puzzles and read her book [1] cover to cover. But, I hated the premise of avoiding "false positives". A famous false negative is Max Howell [2] (who went on to write Apple's Swift Package Manager)
So, how did I get a gig? I kept trying. Learned new frameworks. Focused on jobs interviews which had a take home. During the on-site, I insisted on using my own laptop. An often overlooked factor in achieving a coding flow-state is muscle memory.
I've been told that some companies are shifting from whiteboard to take-home -- particularly during covid. Post covid, if the option is available to you, try moving to the Bay Area or Austin and attend every single hackathon that looks interesting. If you don't want to leave HI, maybe contribute to an open source project in some way.
Or perhaps, start a company. Maybe there's an opportunity in refactoring Aerospace code? I dunno. Now, I'm guessing ...
[1] https://www.amazon.com/Cracking-Coding-Interview-Programming...
[2] https://news.ycombinator.com/item?id=9695102