There are two things at play here. One is your core competency and two is your DSA skill.

For core competency, you need to have a decent understanding of how big systems work at scale.

For DSA, you should be comfortable with LC mediums at least.

Other than this, you are also expected to know PHP, JS & MySQL in depth. I would personally suggest choose either PHP or JS and make it your primary skill.

I have personally done this in past, DM me if you want to discuss more.

Transitioning from backend development to big tech giant companies is achievable with a strategic approach. Here are steps to follow:

1. Skill Enhancement: Strengthen your primary skills in Laravel, PHP, JavaScript, and MySQL. Expand your knowledge in Node.js, React.js, and MongoDB to align with industry demands.
2. Portfolio Development: Build a robust portfolio showcasing your backend development projects, emphasizing scalability, performance optimization, and security implementations.
3. Leverage Open Source: Contribute to open-source projects related to your skillset. This demonstrates your expertise and collaborative abilities.
4. Networking: Connect with professionals in big tech companies through LinkedIn, industry events, and meetups. Networking can provide insights and potential job opportunities.
5. Prepare for Interviews: Practice coding challenges, system design interviews, and behavioral questions relevant to big tech companies' hiring processes.
6. Research and Apply: Research companies aligning with your career goals and values. Tailor your applications and resume to highlight relevant experiences and achievements.
7. Continuous Learning: Stay updated with the latest technologies and trends in backend development. Demonstrate a commitment to lifelong learning and adaptability.

By following these steps, you can increase your chances of securing a role at big tech giant companies, leveraging your backend development experience and expanding your skillset to meet their requirements.

Preparation of tech giants majorly involves problem solving. Practice DSA. Topics like Dynamic Programming, Tree, Graph, Heap, Stack, Queue, Sorting, Searching, Array, Linked list etc. Since you have 4 years of experience, expect System design questions too in the interview. This includes both High level and low level design. Lastly brush up OOP concept, CS fundamentals (Specially Database), Multithreading, your skills which you have mentioned above (you should completely know your projects and tech stack). For behavioral rounds, lookup on internet and prepare for various scenarios that might have happened in the work experience. That's pretty much it.

For more detailed roadmap, resources and mock interviews, you can reach out to me via trial sessions/LTM sessions.

All the best!! ☺️

This might sound controversial but your previous technologies or proficiency on any particular tech stack holds little to no relevance in getting job at top tech giants.

At your level of experience what will matter is:

1. DSA/algo skills
2. Way you solve and code problem in coding interview
3. LLD/HLD knowledge (for some companies)

You can get referral easily, no need to spend time on open source and portfolio development. These might matter for a startup but no one in top tech giants pay attention to these things at time of recruiting. You'll automatically learn these on job itself. Focus on DSA/LLD/HLD concepts and a strategic way to crack interview. You might not use same things on job but it is what it is. We can either whine about it or understand the system and make best for ourself. For further clarification, you may look at my profile!