Covering eyes for Shma which isn't THE shma

Question

Based on the answer to this question about covering ones eyes for the Shma said early in davening, it would appear that one only covers his eyes when saying the verse of Shma in order to enhance the kavannah in order to fulfill the obligation of saying Shma. If he will be able to say the Shma and its blessings within the proper time, he need not cover his eyes when he says the verse earlier in Davening.

One of the reasons we insert Shma in the kedusha of musaf (according to the research I did for this question) is because its being said had been outlawed. If so, then saying it in musaf became the time to fulfill the obligation of saying Shma -- would the eyes have been covered then?

And in Kriat Shma al Hamittah (according to the handy Artscroll siddur) one must cover his eyes as well -- and yet this recitation is NOT about fulfilling that obligation to recite the Shma, assuming ma'ariv has been said at a late enough time. So why would there be any eye covering there? If it is simply about kavannah when davening, wouldn't it be appropriate to cover eyes ANY time we say the verse?

Answer 1

The Shulchan Oruch in 61 (1) says

יִקְרָא קְרִיאַת שְׁמַע בְּכַוָּנָה, בְּאֵימָה וּבְיִרְאָה, בְּרֶתֶת וָזִיעַ.

The Mishnah Berurah in 61 [3] comments:

ג) באימה ויראה - ונראה דאימה ויראה זו היא באופן זה שיכוין בשעה שהוא קורא את שמע לקבל עליו עול מ"ש להיות נהרג על קידוש השם המיוחד דזהו בכל נפשך אפילו נוטל את נפשך ועל זה אמר הכתוב כי עליך הורגנו כל היום כי אז בכונה זו יקראנה באימה ויראה ורתת וזיע

The words באימה ויראה imply accepting G-d's absolute sovereignty.

So we see that there are two mitzvos to be done with Krias Shema. One is the mitzvah of Krias Shema itself and the other is the mitzvah of accepting G-d's absolute sovereignty.

Although there may be times when we say (part of) Krias Shema when there is no obligation for the mitzvah of Krias Shema itself, this does not necessarily take away the need to be מקבל עליו עול מ"ש to accept G-d's absolute sovereignty when we say it. The covering of the eyes can be to have intention to accept sovereignty.

This could contribute to the reason the Ben Ish Chai quoted by @Hacham Gabriel insists on covering the eyes for “Qeriat Shema prior to Parashat HaTamid”.