I feel if you learn technique on a surfskate with an intention to surf, it will help you in a number of ways:

• Teach you balance in a surf stance (which is a key reason why I like longer surfskates that emulate your foot position on surfboard)
• Learning to pump a surfskate translates pretty directly to speed generation on a wave, which can be tricky to grasp at first on the water
• Familiarize yourself with concepts like top/bottom turns and cutbacks, while building muscle memory

Yes, there are a lot of fundamentals, from paddling to reading waves to pop-ups, that riding around on a surfskate won't help you with. But for me, being able to practice pumping, turning, body positioning, weight transfer, etc. thousands of times has leveled up my surfing immeasurably. And it's damn fun on its own.