Here in the printer’s manuscript, Oliver Cowdery initially wrote unto (thus “unto your own land”); then virtually immediately he overwrote the u with i, giving “into your own land” (there is no change in the level of ink flow for the correction). 𝓞 is not extant for the preposition, but it probably read into (given the virtual immediacy of the correction in 𝓟). Moreover, other instances of the verb follow have into, not unto, for the following prepositional phrase:
Alma 28:1 behold the armies of the Lamanites had followed their brethren into the wilderness
Alma 58:19 therefore they did follow us into the wilderness
Of course, these two instances refer to following someone “into the wilderness” rather than “into a land”. Nonetheless, these examples are consistent with the corrected reading in 𝓟 for Alma 54:12. The critical text will retain the preposition into in this passage.
There are many instances in the manuscripts where Oliver Cowdery accidentally wrote unto instead of the correct into; for a list, see under 2 Nephi 8:23. So the momentary error here in 𝓟 for Alma 54:12 is not surprising.
Summary: Accept in Alma 54:12 the corrected reading of the printer’s manuscript: “and I will follow you even into your own land”.