'worked at startups and established companies and built a variety of systems at scale - frontend, backend, db and client' These companies, and especially the i

'worked at startups and established companies and built a variety of systems at scale - frontend, backend, db and client' These companies, and especially the interviewers, don't care about any of that. They only care about algorithms and puzzles. There are plenty of sites that cover all the typical algos and puzzles that interviewers like. Just practice those over and over.