Is It Ok To Have A Gift Card Only(for Later Use) Baby Shower?

I don't see where there would be a problem to do that.  It is actually easier for people to just get a gift card than going through some of the registries and trying to find some of the items on the list.  I think that sounds like a good idea.  Good luck with your baby shower!

I think it's perfectly fine. The parents can use the gift cards to buy exactly what they want for the baby, instead of having to rely on the guests to buy stuff they think the parents will want, like clothes, toys, etc.

A gift card is always the best idea! Especially virtual gift cards like those reviewed by https://giftcards-market.com/ . I suggest

gift cards to something like Babies r Us, target, or diapers.com (or anywhere you can order baby stuff online and have it shipped, as getting to the store can be a challenge early on). Or maybe a gift card for a favorite local restaurant that does take-out, to give mom an option other than cooking (the best things I've received after giving birth were home cooked meals from others in the first weeks after coming home).