You can win local customers without a Google Business Profile. It is not a requirement. It is, however, the highest-return hour most local businesses can spend, and going without means doing more work elsewhere.
What you lose without one
The map pack, which sits above the organic results on almost every local search. The knowledge panel on brand searches. Reviews shown directly in results. Directions, click-to-call and hours surfaced without anybody visiting your site.
What you would need to do instead
Build service and location pages that name each area you cover, with the place name used naturally in the title and the first heading. State your service area plainly in the footer, on the homepage and on the contact page. Add LocalBusiness structured data so search engines can read your details without guessing. Publish a FAQ answering the questions customers in your area actually ask, which also gives you a shot at appearing in AI answers and featured snippets. And keep the technical side clean: fast, mobile-friendly, HTTPS.
The honest recommendation
Do both. The profile takes an afternoon to complete properly and starts working within weeks. The site work compounds over months. Skipping the profile to rely on organic pages alone means competing from below against businesses appearing above you in the map.