One must have kavanah (intent/concentration) in the first bracha of Shemoneh Esrei. And if he didn't, he would have to repeat it. See the g'mara in B'rachos 34b:
איכא דמתני לה אברייתא: המתפלל צריך שיכוין את לבו בכולן. ואם אינו יכול לכוין בכולן יכוין את לבו באחת. אמר רבי חייא: אמר רב ספרא משום חד דבי רבי: באבות
Does this also apply to the verse "Hashem sifatay tiftach ufi yagid tehilatecha" said before beginning the first bracha?
The Mishnah Berurah OC 111 (1) [1] says about אדני שפתי תפתח וכ׳:
פסוק זה מכלל תפלה הוא דהא מהאי טעמא נוכל לומר אותו בין גאולה לתפילה מפני דכיון דקבעוהו רבנן בתפלה יש לו דין תפלה
that it is part of the Tefillah.
The מחזור מסורת הרב (K'hal Publishing) quotes the hanhagos of Rav J B Soloveitchik. He insisted that the chazzan must
“recite each and every word of the repetition of the Shemoneh Esrei out loud, including the introductory verse אדני שפתי תפתח וכ׳."
This is more strict than the standard ashkenazi practice which is to say it quietly. We see that Rav Soloveitchik was strict in this respect with the introductory verse.
It is well established on this site that “Absence of evidence is not evidence of absence”. Nevertheless, I want to suggest that had Rav Soloveitchik held that kavanah in אדני שפתי תפתח וכ׳ was essential, this would have been recorded in the Hanhagos Harav.
None of the commentators in Sefaria on the Shulchan Oruch OC 111 goes further than saying that אדני שפתי תפתח וכ׳ is part of the tefillah.
On these grounds, I suggest that it is most unlikely that kavanah for אדני שפתי תפתח וכ׳ is essential to the extent that if one does not have kavanah one has to repeat the Shemoneh Esrei.
Rav Moshe Feinstein in Igros Moshe vol. 8, Orach Chayim 24:8 discusses the closely related question of whether the opening (this one) and closing ("...יהיו לרצון") verses that surround sh'mone esre must be said at all (לעיכובא). He holds that in this day and age - when there are no karbanos - they must. In principle, not saying either of those lines would call for one repeating everything from that point on (though this applies differently to the closing pasuk than the opening one).
From the 3rd page, righthand column:
אבל פשוט שמי שטעה בתפלתו באופן שצריך לחזור לראש כשהוא עדיין עומד בתפילה, שלא עקר רגליו, שלא יצטרך לחזור אלא לתחלת ברכה ראשונה שהוא מ"ברוך אתה ה׳", לא מ"ה׳ שפתי". מאחר דהתפילה עצמה מתחלת בברכה ראשונה שהוא מריש הברכה, שהתחלתה הוא מ"ברוך אתה ה׳" דברכת אבות.
Obviously somebody who erred in his t'fila in a way that requires him to return "to the beginning" while still standing in t'fila [mode], having not moved [from his position], would only need to return to the beginning of the first b'racha, i.e. "ברוך אתה ה", not [to] "ה', שפתי".
So if one were to have to repeat that prefatory pasuk it would be for its own sake, and not because it is part of the first b'racha.
Further on, he explores the hypothetical situation in which an audience member is relying on the sh'liach tzibur to recite the amida by proxy, as opposed to the common practice today of listening intently to the repetition thereof after having discharged each of our personal obligations ourselves. He assumes that even those who are not well enough versed to say the whole amida could still learn or repeat word-for-word the verse in question, and that they would do so right before the repetition. However. . .
ואם היה מזדמן אחד שגם לומר עם אחר לא היה יכול לומר אף רק פסוק זה, היה פטור מטעם אונס.
If there were a person who was unable to say even this sole pasuk [by repeating after] another person, they would be exempt due to [the technical exemption from obligations that arises in the presence of uncontrollable external] forces.
While this does not address saying the words without intent, he seems to be setting the bar very low for what qualifies as prepending "...ה', שפתי" - i.e. repeating another person's words after them. Even if one were required to have some level of intent in saying that line (e.g. knowing that it was one's gateway to t'fila in a general sense) the requirement would be dissociated from the reason making intent during the first b'racha a sine qua non.
