Let me start off by first thanking the Leetcode community especially those who take the effort to explain their solutions in the discuss tab of questions.
My background: MS in CS from a very reputed college in the US and 5+ years of experience as a backend dev.

I have been studying for the past 8+ months while working full-time and I’ve completed over 400 questions on Leetcode.(I don't think the number of questions you solve really matters till you know the basics well)

Since I signed an NDA I can’t really share exact questions but i can mention topics.
The most helpful resources I found - Leetcode, E-d-u-c-a-t-i-v-e g.r.o.k.k.i.n.g courses on system design and coding patterns, in-te-rv-iew cake, gaurav sen and tech dummies on Youtube and cracking the coding interview and I also bought the Algo-Ex-pert and Systems-Ex-pert course.

Companies I interviewed with (in no particular order)
Format -> (company name, how I got the call, experience) - result

-Goldman Sachs (Recruiter reached out) - Couldn’t get past the phone round - 2 qs Graphs(BFS) and HashMap implementation
-Bloomberg (Applied online) - Couldn’t get past the phone round - 2 phone rounds - Stack qs, recursive graph problem + behavioural
-Microsoft - (Recruiter reached out) - phone screen + 4 onsite rounds - array qs, caching algo, string manipulation + behavioral in each round - (Reject)
-Amazon - (Recruiter reached out on LinkedIn) - OA + Phone screen + onsite loop - OA ( Qs from list), Phone screen - String manipulation, Loop - behavioral + coding (very practical qs not from LC) + LP + system design (Result pending)
-CBS Interactive - (applied online) - phone screen + loop - system design + string manipulation + lots of basic programming qs + behavioral - (Offer)
-Pinterest - (Applied online) - Phone screen + onsite loop - all practical qs - nothing like leetcode qs + behavioral and system design - (Offer)
-Oracle - (Applied on Linkedin) - Phone screen + onsite loop - basic DS question - system design + behavioral + api designing qs + hashmap implementation - (Offer)
-Remitly - (Applied online) - Phone screen - string manipulation - (onsite pending)
-Epsilon - (Applied on LinkedIn) - Phone screen + onsite loop - mix of everything in every round - Lots of Rest and Api design, system design and behavioral - (Offer)
-Apple - (Recruiter reached out) - Phone screen (lots of behavioral) + Phone screen 2 (system/OOD - I still dont know what this round was) - (Reject)

My decision is still pending with a couple of companies. Still talking about the TC and other details.

My Overall Experience:
This has been a totally grueling 8-9 months. The stress of losing a job during a pandemic added to the overall chaos in life.
But I am happy that I am on the other side now. I experienced all the kinds of interviewers - some where really great, some just gave you a question and did not bother to work with you or discuss the approach or anything. My points of advice would be - KEEP TALKING! Just keep talking through your approach and anything and everything you have on your mind. Keep them engaged! Keep a bottle of water next to you because you will get thirsty with all the talking :)
Ask questions, clarify requirements, write down a rough pseudocode or approach but don’t take up a lot of time doing this, make sure your code is clean, has good variable names and run through with an example before you say you’re done! Try to follow best coding practices as much as you can.

If you practice LP questions properly for Amazon, you’ll be able to crack any behavioral interview- DO NOT TAKE THIS LIGHTLY!

I have learnt a lot and failed a lot - but now that I am on the other side of this… I can say it was all worth it!

Keep Dreaming, Keep working hard and slowly but surely - you’ll get there!
GoodLuck!