What is the least amount of effort to setup a Monero address like a tip jar, deferring transfers and if necessary even checking the balance until setting up something more full-blown later?

Check out feather wallet (https://featherwallet.org/) on desktop or cake wallet (https://cakewallet.com/) on mobile.

Once you create a wallet and write down the seed phrase, generate a "view key". Creating a new wallet from this "view key" allows you to see incoming transactions to your addresses, but not spend them. So you don't need as much security for "view-only" wallets.

You can generate an address from either wallet. It's a long string of numbers and letters that begins with an "8", under "Receive".