Hi @dievardump,
First add your configuration files to version control: https://docs.openzeppelin.com/upgrades-plugins/1.x/network-files#configuration-files-in-version-control
I installed Hardhat in the existing project that deployed using Truffle.
Upgrades Plugins uses their own Network Files (https://docs.openzeppelin.com/upgrades-plugins/1.x/network-files#network.json), so these are the files we need to focus on rather than Truffle artifacts.
deployProxy should only deploy a new implementation contract if the bytecode has changed, but I would check this on a public testnet first when migrating from Truffle to Hardhat. In case you are changing anything which results in a bytecode change.
An upgradeable contract has an implementation contract, a ProxyAdmin and a proxy. ProxyAdmin is per project and per network, so if the implementation contract hasn't changed, then only a proxy should be deployed.