I have been reading about Polkadot transaction fees (https://wiki.polkadot.network/docs/learn-transaction-fees) and understand at a high level the weight-based model, and that this is calculated prior to the transaction vs. a benchmark, as opposed to gas metering which is calculated differently, but they are both still transaction fees, correct? Albeit Polkadot's are cheaper and less variable? Is it accurate then to say that Polkadot is "gas-less", but not "fee-less"? - as I have heard the former attributed to Polkadot and it confused me. Thank you!
As you can see from the reference you linked, (most of) transactions in Polkadot relay chain pay an inclusion fee, so I would say that calling Polkadot "fee-less" is a misconception.
However, there are exceptions to this and certain types of extrinsics are excluded from paying fees. This is the case of unsigned transactions (claim DOT token, heartbeats...). Since there is no key pair associated to them, fees can't be taken from any account. But bear in mind that unsigned transactions are only used in special cases and each one needs its own, custom validation logic.
Since Polkadot relay chain is a Substrate chain, I recommend you to read about fees and weights on Substrate chains. Also if you are interest in exploring feeless transactions and how to implement them on a Substrate chain, have a look to this Substrate Exchange question.