The sources assembled here do not converge on a single question; rather they are a scattered collection of passages that happen to touch on the word קץ/סוף ('end') in various unrelated contexts. Rashi (Bereishit 41:1) simply glosses the word מקץ as meaning 'at the end,' noting that every form of קץ denotes an end of some kind, while Rav Samson Raphael Hirsch likewise explains קץ as the point where something stops.
HaKtav VeHaKabalah (Devarim 15:1) takes up a specific dispute about this same word in the context of shemittah, citing the Ibn Ezra's view that מקץ means from the start of the year, against the position that it refers to the end of the seven years, and he distinguishes the related term קצה as denoting a partial endpoint in place or time rather than an absolute terminus.
Recanati (Noach:2) uses the term קץ in a wholly different sense, identifying 'קץ כל בשר' with the attribute of Divine judgment that takes life, drawing on a derivation from Kohelet and a Midrash about the elements executing judgment because the earth was filled with violence.
Targum Jonathan (Yehoshua 1:11) uses the cognate 'בסוף תלתא יומין' simply to mark a count of three days before crossing the Jordan, and Midrash Tanchuma (Ha'azinu 5) discusses Divine righteousness toward the poor without engaging the term קץ at all.
The Talmudic sources cited — Pesachim 94a:2-3 on exemption from the Paschal offering for one delayed on the road, Shabbat 34b:2-3 on the uncertain status of twilight, and Pesachim 2a:1 on the obligation to search for chametz — address distinct halachic topics of travel, twilight, and bedikat chametz, and none of them bears on the linguistic or conceptual question of קץ/end that the other sources raise.
Shulchan Arukh, Orach Chayim 32:1 likewise addresses an unrelated matter, the required order of the four parshiot written in tefillin, and offers nothing toward the question posed.