Investing in Oman can be influenced by various factors, including market demand, economic trends, and regulatory considerations. As of my last knowledge update in January 2022, some types of shops that may be considered relatively safe for investment in Oman include:

1. Grocery Stores:  Essential goods, including groceries, are consistently in demand.

2. Pharmacies:  Health and wellness-related businesses, such as pharmacies, tend to have stable demand.

3. Clothing Retail: Fashion and apparel, especially modest and traditional clothing, are popular in Oman.

4. Electronics and Appliances: With the increasing use of technology, shops selling electronics and appliances may find a stable market.

5. Food and Beverage Outlets: Restaurants, cafes, and eateries catering to local tastes and international cuisine can be successful.

6. Car Accessories and Services: Given the importance of transportation, shops offering car accessories and services may have a steady customer base.

7. Home Furnishings: With ongoing construction and housing projects, shops selling home furnishings and decor may find opportunities.

8. Beauty and Personal Care: Beauty products, cosmetics, and personal care items are in demand.

9. Health and Fitness: Gyms, fitness centers, and shops selling health-related products can attract customers.

10. Children's Products: Shops specializing in children's clothing, toys, and educational products may be well-received.

Before investing, it's crucial to conduct thorough market research, understand local regulations, and consider the specific needs and preferences of the Omani market. Consulting with local business experts and authorities can provide valuable insights into the most viable investment opportunities. Keep in mind that economic conditions and consumer preferences can evolve, so staying informed about market trends is essential.