Not all P2P platforms are no KYC, Binance P2P is the example of P2P platform that would ask KYC.
To be able to use P2P, all must KYC, this is to prevent money laundering and trade fraud.
You're wrong to suggest Pancakeswap and Uniswap as the decentralized exchange to buy Bitcoin, there's no way you can buy Bitcoin using Pancakeswap and Uniswap since they're only use ETH and BSC chain. You're only can bought fake Bitcoin e.g. BTCB (Fake Bitcoin run in BSC chain) and WBTC (Fake Bitcoin run in various chain). It's not even a decentralized exchange, but a swap exchange.
Yes, the bitcoin you get here are not real bitcoin.
The only truly decentralized exchange is only Bisq and it's not good to use Kucoin as been stated by @o_e_l_e_o above.
As for buying bitcoins on Kucoin exchange, I don't think it is too bad since they do not force you to do KYC, there might be some limitations with non-KYC accounts, but I do not see too much impact on Bitcoin buying as a whole. You can buy bitcoin on kucoin and then you can transfer it to your personal wallet it doesn't reveal your identity.