Resources
OAuth 2.0 for NetSuite - Part Three - PKCE
The NetSuite documentation on Authorization Code Grant Flow states that the use of PKCE is optional, except in a couple of

Passionate about all things NetSuite dev and Computer Science
Founder & Creator of Bundlet. Bundlet emerged from our founder’s early work experimenting with SDF, building deployment pipelines for NetSuite development, and exploring the legacy NS Cabinet npm package.