We spend a lot of quality time in our shops, it should be a pleasant place. And it may be important to you that dust doesn't adhere. If you have particle board or OSB walls you might want to upgrade them. Three approaches seem good.
Cover them with prefinished wood paneling. This is quick and inexpensive and is reasonably durable. Mine is wood panel up to 4 ft and white above.
Paint with several coats of whatever till smooth. On one project I asked friends if they had leftover interior paint to give away. This produced plenty, including one 5 gallon pail of too white ceiling paint. I mixed it all into a mud colored soup and painted on a few coats, then applied a finish coat that I bought. Worked out great though still not really flat.
Now I would apply a skim coat of drywall mud and then paint.