Still like to get my kids a Valentine “treat”. Two are paired with a significant other and the youngest is not at this time. One couple is in town so I can pick up a certificate or bake a treat and drop it off.
I may just send a gift card electronically to the ones with significant other - enough for an easy dinner out.
I was also looking quickly at Amazon to do a last minute candy delivery - some usual brand decent chocolate.
When I was looking to have a birthday cake delivered to my D’s college I found a website called gold belly. They ship food from all over the country anywhere you want - everything from cakes to turkeys to lobster rolls. You can sort by type of food, type of celebration or region. I ended up using a local bakery but I am going to keep this in mind for other gifts.
Some restaurants do electronic gift cards. Perhaps you can find a good hot spot in their location for a night out on you. Mine would prefer that to fruit, flowers, or candy.