Is there a single webpage that lists the current transaction fees for the major blockchains, like BTC, ETH, solana, avalanche, matic, BCH, BSC, etc?
I don't think it is possible to create such a comparition.
It's possible lol. don't you ever get a common knowledge about programming? Any blockchain has API and you can take the data from the blockchain use API i.e transaction fees, block reward and many more. It's possible to create a chart that was connecting to the API from the specific blockchain like ETH, BSC or matic.
Transaction fees change when the number of transactions on a given blockchain changes. It may be a greater or lesser amount at any time.
When it comes to Bitcoin's blockchain, the current fee status can be checked on the website:
https://bitcoinfees.earn.com/Yeah but in this case you are taking only the transaction fees on the blockchain and you didn't take the total transaction fees. It's also fluctuating based on the transaction in the blockchain. It can be checked into the various sites but i should remind you that it's possible to build a website that shows you average fees in the various blockchain.