Can you use a crossbow For target shooting?

Generally speaking, crossbows can be used for target shooting only if you are practicing or maybe with friends. However, when it comes to competitions, most do not allow it because crossbows are often more potent than normal compound bows, which will result in unfairness.

Which one is more convenient to use?

If you are thinking in the sense of compound bow vs crossbow, then, Compound crossbows are comparatively easier to use than Crossbows. Archers don't have to adjust the bolts, cock, and then shoot. In a compound crossbow, you just have to take out the arrow, adjust the string, and then shoot!

Do crossbows have different maintenance than compound bows?

Yes, crossbows are more difficult to maintain than compound bows. A compound bow needs regular checkups for wear and tear, whereas the situation is totally different with the crossbow. If you aren't checking the crossbow and it has malfunctioned, there is a huge chance it may damage or hurt you while shooting.