Now couplets cannot be hung on the wall with hooks, so there are couplets that can be hung on the wall with hooks.

The couplets that you said can be hung on the wall with hooks are called "nave", which are specially mounted and there are no ready-made goods on the market. As shown in the figure:

You can go to the painting and calligraphy mounting shop and ask the store to provide nave with corresponding content and size or put your existing calligraphy couplets, so that the store can mount them for you.