I use OpenJSCAD for 3D printing, mostly, and have been tracking V2 and able to make the things I needs without too much issue. I have a package.json with:
"main": "index.js"

Then an index.js like:

//include your script here:
var inc = require('./mypart')

const getParameterDefinitions = () => {
    return inc.getParameterDefinitions()
}

const main = (params) => {
    return inc.main(params)
}

module.exports = { main, getParameterDefinitions }

The do my parts like:

/* All the csg API functions: */
const { cube, sphere, cylinder, geodesicSphere, torus, polyhedron } = require('@jscad/csg/api').primitives3d
const { circle, square, polygon, triangle  } = require('@jscad/csg/api').primitives2d
const { difference, union, intersection } = require('@jscad/csg/api').booleanOps
const { translate, center, scale, rotate, transform, mirror, expand, contract, minkowski, hull, chain_hull } = require('@jscad/csg/api').transformations
const { extrudeInOrthonormalBasis, extrudeInPlane, extrude, linear_extrude, rotate_extrude, rotateExtrude, rectangular_extrude } = require('@jscad/csg/api').extrusions
const { css2rgb, color, rgb2hsl, hsl2rgb, rgb2hsv, hsv2rgb, html2rgb, rgb2html } = require('@jscad/csg/api').color
const { sin, cos, asin, acos, tan, atan, atan2, ceil, floor, abs, min, max, rands, log, lookup, pow, sign, sqrt, round } = require('@jscad/csg/api').maths
const { vector_char, vector_text, vectorChar, vectorText } = require('@jscad/csg/api').text
//const { echo } = require('@jscad/csg/api').echo
const {CAG, CSG} = require('@jscad/csg/api').csg
const { extrude_text } = require('./fonts/index.js')

const paramDefaults = {size: 10}

const getParameterDefinitions = () => {
  return [{ name: 'size', type: 'int', initial: 10, caption: 'Size?' }]
}

const main = (params) => {
	params = Object.assign({}, paramDefaults, params)

	let results = []
        // replace this
        myPart = cube(params.size)
	results.push(myPart)
	myText = extrude_text("Blank Project", 1, 1.5, {height:5, font:'camBamStick1Font'})
	myText = translate([-45,-10,0], myText) 
	results.push(myText)

	//

	return results 
}
module.exports = { main, getParameterDefinitions, paramDefaults }

Then I just drag the folder to my browser running the web application.
The "extrude_text" include is my integrating the single-line fonts from https://github.com/lautr3k/jscad-vector-fonts

Now that a lot of the csg integration to packages/modeling has happened (Thanks kaosat-dev!) it works for me to replace stuff like:

const { cube, sphere } = require('@jscad/csg/api').primitives3d

with:

const modeling = require('@jscad/modeling')
const { cube, sphere } = require('@jscad/modeling').primitives

Is there a "recommended" project layout out there on a wiki somewhere? Would it be helpful for others if I post my "blank project" to github?