Using Indexer which address I need to search to get the buy or sell transaction of ALGO, I want to track the transaction of ALGO itself is it possible ? if so which API to use, whats the address to use on Indexer
Welcome to Algorand!
I would recommend to read Indexer - Algorand Developer Portal that explains in more details each endpoint.
From the blockchain point of view (and hence the indexer point of view), you will only see transactions: when an address A sends Algos to an address B.
The indexer won’t tell you if it’s selling (which I understand by sending Algos in exchange for another currency) / buying (which I understand as receiving Algos in exchange for another currency) / or something else (e.g., lending / borrowing / paying for another purpose / …).
Centralized exchanges anyway do not publish on chain their selling/buying trades, so there is no way you can actually figure that out. (Using some additional work, you can however figure out when an address deposit and withdraw money to an exchange, but this still won’t indicate selling/buying.)
For decentralized exchanges / DeFi (such as https://tinyman.org/ or https://www.algofi.org/), you need to handle each DeFi app individually.