PS: You already have a solid foundation in computer science and software engineering
Any technology you can pick up in three months that would secure a job "right away" would already have hundreds of thousands of people doing the same thing, competing for the same jobs. You won't find any shortcut or one weird trick no one else knows about to get a job.
You may have noticed the short supply of tech jobs right now, and lots of people looking for jobs because of waves of layoffs. And you may have read about many major employers, especially in the tech sector, reining in remote workers and enforcing return to office policies. Finding any job right now presents big challenges, and finding a remote job now will prove even more challenging.
Instead seek entry level certifications. I recommend Security+ and what ever the entry level AWS cert is.
If you want to ignore all this advise and absolutely have to focus on a technology skill then master everything there is to know about data transmission. Learn the OSI model, HTTP, WebSockets, gRPC, certificates, and so on. Read the RFCs several times. In order to really attain mastery you should plan on studying 45-50 hours per week minimum with that time being intense dedicated focus.
Transmission mastery is what got me my current job, but in all fairness I was at it for more than 3 months. I had written an original WebSocket library a few years earlier and improved upon it over time. Despite the current industries most esteemed experts telling me one thing regarding the relationship between HTTP and WS I was able to prove them wrong, with working code, by demonstrating that HTTP could be served over WS and that WS does not have to be served over HTTP as many claim. Insights like that takes longer than 3 months to realize.
Filters: Worldwide
Remote
Experience Level: Date: Last Week Go through the results and look for jobs that you like. Read the requirements and try to target those skills.
Also search for "certification" or "skill you have".