I'm trying to set up SuiteCommerce Extension Developer environment, and I'm at the step where you type "gulp fetch", and it keeps saying I need "key" and "secret", but those were never mentioned in the SuiteAnswers article, so I don't know if I need to set up an Integration and an Access Token in NetSuite or what. Instead, can I make this authenticate the way SuiteCloud Developer Framework does in Visual Studio Code, where it pops open a browser window and you click a button to authenticate?

For SuiteCommerce, I don't think so (but someone correct me if possible) - I've only ever used the Access Token and then putting the key/secret in the .env file

Shelby is correct. Per the docs: https://docs.oracle.com/en/cloud/saas/netsuite/ns-online-help/section_1518824336.html#subsect_24235436762

Thanks for the help. I got it working using browser-based authentication. I had to create an Integration with certain settings for TBA and User login credentials, and also a localhost callback URL on port 7777 (which is coincidentally the same port number used by default for Unreal Engine projects; totally unrelated), that's all as per SuiteAnswers. The Integration's Consumer Key and Secret go in the developer tool's root folder in the .env file. Once that's in place, the gulp extension:fetch --to command pops open a browser window using the Integration to generate what I think is a per-session Access token, and then clicking the button in the browser allows the process to continue from there, and a New Token is created for the extension developer tools, using a name I type in. Summary: I was able to get the fetch command to work, I just had to create an Integration. This is basically the exact same way I authenticate my SuiteCloud Developer Framework projects in Visual Studio Code.