Yes it’s OK, but it can be a trap. Many toddlers get stuck on certain foods, otherwise known as a food jag.
These are typical of the toddler years and are characterized by eating the same foods day in and day out. Generally, food jags are self-limited. They fade over time when parents don’t draw too much attention to them, cater to them, or pressure their child to eat other or certain foods.
Parents can get trapped by a food jag when they don’t offer other foods or let the food variety dwindle. So, the daily hot dog isn’t the end of the world, but you will want to keep other foods showing up on the tray — plenty of other protein sources, fruit, vegetables, dairy and grains.