There is a Midrashic approach to "and they stood at the foot of the mountain" (Shemos 19:17), namely that G-d literally held the mountain over the heads of B'nei Yisrael, coercing them to accept the Torah (See for example Shabbos 88a).
The Midrash Tanchuma (Noach 3:4) says:
The Israelites did not accept the Torah until the Holy One, blessed be He, arched the mountain over them like a vessel, as it is said: And they stood beneath the mountain (Exod. 19:17). R. Dimi the son of Hama stated that the Holy One, blessed be He, told Israel: If you accept the Torah, well and good; but if not, your grave will be there.
In Toras Avigdor by Rav Avigdor Miller (Parashas Yisro, p. 108) it says on the concept of "na'aseh v'nishma":
It means they accepted everything beforehand, before they even knew what would be expected of them. If Hashem would tell them to stand on their heads every morning for ten minutes, they would do it.
Saying na'aseh v'nishma, B'nei Yisrael is praised, because we wanted to fulfill G-ds mitzvot even before He told us to do it. However, the teaching of the Gemara and Midrash, that we were coerced, seems to contradict this. First of all, the pasuk never says G-d held the mountain over the heads. Similary, the Or HaChaim teaches us the opposite:
ויוצא משה את העם, Moses lead out the people, etc. Perhaps this was necessary because the people had become afraid of the Mountain by now. Moses took them to the edge of the Mountain so that they would accept the Torah while standing there.
The Gemara further states:
If you accept the Torah, excellent, and if not, there will be your burial.
If you ask me, if someone was treathing me to do something, and I knew it was a case of life and death, I am sure what I did. How then is this considered as "na'aseh v'nishma"? How is this considered voluntarely?
Thanks to Joel K. for pointing out the Tosfos on this Gemara. The Tosfos explains:
Answer (R. Tam): [Both of those] were based on Hash-m's command. It is as if they were coerced. However, in the days of Achashverosh, they willingly accepted [Torah] due to love of the miracle.
The point is, Matan Torah is such an important date in our history. Why then can it teach us that we accepted G-ds Torah only out of "fear" (coercion) and only until Purim out of love?
See also the Rashba on Shabbos 88a:5 which explains (cited by Steinsaltz) that "holding the mountain above the heads" alludes to the love G-d showed the people during the exodus out of Mitzrayim, and because of that, they said Naaseh VeNishmah. But this does not apply to the later generations, only to that generation.
Miller, R. A. (2020). Toras Avigdor, Vol. 2 - Shemos. Judaica Press.