What is the difference between a SAS and a SASU?
A SASU is a SAS with only one partner.
The applicable legal regime is, therefore, the same.
The documents proposed by alf.com anticipate changes in the distribution of capital and allow your company to be governed in the same way with one or more partners.
You can incorporate your own company and, without having to change the corporate governance, add one or more partners in the future.