A lot of people seem to be confused on what to do after the merge.
Lets look at an example of post-merge network. The Görli testnet merge has already been completed, so we can use the explorer to see how it works now.
The transactions on Görli are already on proof-of-stake consensus. However the same explorer, wallets continue to support the post-merge Görli, and the same dapps work on PoS Görli as well.
For wallets, the same wallet that you use will continue to support the PoS network. If you had testnet coins on Gorli before the merge, you can continue to transact with these coins, just like before with no changes whatsoever.
So for an end user, absolutely nothing has to be changed. If you want to swap or lend or use any other dapp, it will be the same as before.
The main internal change that an end user can see is that the mining difficulty will become zero post-merge.
This is a pre-merge block on the Gorli testnet: https://goerli.etherscan.io/block/5000000
This is a post-merge block: https://goerli.etherscan.io/block/7496218
On comparing both, you can see that difficulty has become zero in the post merged network, and total difficulty has been permanently frozen at 10,790,000. The same cam be expected for mainnet as well, as mining is phased out, the difficulty will become zero and total difficulty will be frozen at the last PoW block.
Regarding forked PoW chains: Its possible that few forked chains emerge during the change in consensus. However, none of the major dapps will support the forked chains. Major oracles like ChainLink have already indicated they wont support any forked chain. Even stablecoins and other key infrastructure wont support the forked chains. Without these things, there are no value in forked chains. However, there is a big risk of replay attacks, and furthermore a scam dapp could use your wallet’s signature on another chain to steal your funds on the main chain. So be wary of signing anything on unknown dapps or websites that may pop up.
TLDR: No UX changes for end user. You can continue using dapps just as you do now. Be wary of new/unknown dapps