The public mempool works the same in PoS as in PoW — anyone running an execution client (e.g. geth) can read transactions from the mempool.
It should be noted, however, that the post-merge public mempool may not see as much activity as it does today. With PBS, users and wallets may choose to send all of their transactions to a specific builder (or builders) rather than to the public mempool.
If public mempool might not see much activity post merge , as an individual, does it make sense to be a builder ? How would users discover me (as a builder) and trust to send me txn to buid block .
Is it possible to differentiate between transactions coming from the public mempool and transactions from private orderflow? (Without running a full node and comparing to the tx you’ve been gossiped)
Maybe transactions with 0 gwei as validator tip?
But I guess that would only catch private orderflow coming from the wallet-level, and not flows from applications or node providers like Infura. Maybe I’m missing something?
Hey @vishal good question. Being a builder is indeed a way to get more orderflow. As for how you convince searchers to send you their orderflow, that’s up to you 
Check out this post for more information on becoming a builder.
Is it possible to differentiate between transactions coming from the public mempool and transactions from private orderflow? (Without running a full node and comparing to the tx you’ve been gossiped)
You can see blocks proposed via the FB relay (and therefore transactions) here: https://boost-relay.flashbots.net/
However, it’s not possible in that context to differentiate between mempool transactions and original private transactions without doing a mempool comparison. However, you don’t need to sync a full node to view the mempool. A light node will work fine. Also note that no mempool view is 100% complete, so this method won’t be 100% accurate, though you can improve the accuracy by peering with a well-distributed array of nodes.
Maybe transactions with 0 gwei as validator tip?
Transactions w/ 0 validator tip won’t be a good differentiator, as searchers will be using that field to bid for inclusion.
Ah, I didn’t realize searchers used the tip field to bid for inclusion, but it makes a lot of sense. Thanks!