I feel my prayers are so full of distraction and half-heartedness that they must be hollow. Are hollow deeds better than no deeds at all?

Start here: a prayer in which the mind wanders is not a hollow prayer. The standing, the bowing, the placing of your forehead on the ground, the turning of your body toward your Lord at the appointed hour, all of this is real, and all of it is counted. A wandering thought is a bird that flies through the room; it does not own the house. And each time you notice it has flown and you come back, however wearily, to the words, that return is counted too.

You ask whether a hollow deed is better than none. Before we answer that, see what the Qur’an tells us this prayer was given to do:

“Indeed, prayer restrains from immorality and wrongdoing.”

Qur’an, Al-Ankabut 29:45 · meaning

That is the prayer’s own promise, and the more of the heart we manage to bring to it, the more of that promise we taste. But you are not asked to arrive with a finished heart before you may stand. The prayer is the place where a heart is trained; it is not a prize handed to a heart already trained. On this the people of knowledge are far easier on you than you have been on yourself. They say plainly that a prayer through which thoughts come and go is still a sound prayer, complete and counted, and that a thought arriving uninvited carries no blame at all. Your standing is written, your bowing is written, and each quiet return from a wandering thought is written. The prayer works upon the soul the way water works upon a seed beneath the soil, patiently, whether or not the seed can feel it. Perhaps a prayer you judged half-hearted was the hand that steadied you this very week, when a wrong path opened in front of you and you did not walk down it.

So do not weigh the poor prayer against no prayer at all. The two are not close. What is asked of us is not the occasional flood of feeling but the small stream that never stops:

“The most beloved of deeds to Allah are the most constant, even if they are little.”

The Prophet (peace be upon him), Sahih al-Bukhari (6464) · meaning

Those who study how habits form say something similar in their own plain way: it is the small act repeated each day in the same setting, not the rare burst of effort, that slowly settles into a life, and a day missed here or there does it no lasting harm. So keep coming. Bring your distracted heart to the prayer just as it is, and let the prayer do to it, day by day, what you cannot do to it yourself.

One small step: In your next prayer, take only the opening chapter, Al-Fatihah, and give your understanding to those few lines alone; if the mind goes elsewhere, come back to the meaning of the next word, without reproaching yourself.