Under the published framework an individual applies on her own, without an employer, but the case still proceeds under EB-1 or EB-2, whose eligibility rules apply. The gift changes the process, not the category standards.
No employer is required; category eligibility still is
The official Gold Card page and FAQ describe an individual applicant who pays the processing fee, is vetted and then makes the gift, without any mention of an employer, a job offer or a business plan. That is the feature that attracts a retired owner. The same material says successful applicants proceed under EB-1 or EB-2, which are existing employment-based immigrant categories with their own standards, admissibility screening and annual limits.
The applicant should therefore ask a plain question before paying the nonrefundable fee: which category will her case use and what evidence does that category require from someone who has sold her business and stopped working. The program is recent and its terms may be revised; the answer should come from the current official page and from advice given on the day, not from this summary. Nothing in the framework describes a purchase of residence, and the published wording should be read as it stands.