The evidence on real play applies equally to single-parent households, and the strategies look different. Here is realistic guidance.
The most important finding in the serve-and-return research is not that children need two parents, it is that they need at least one consistently responsive adult. The quality of a single responsive, warm, engaged parent is neurologically equivalent to two distracted or absent ones. Single parents are not at a disadvantage in the research, they are often the most motivated and intentional caregivers precisely because they know the weight falls entirely on them.
Key citation
Sroufe, L.A. et al. (2005). The Development of the Person. Guilford Press · Bowlby, J. (1969/1982). Attachment. Basic Books
For single parents, building a child's capacity for independent play is not a luxury, it is a survival strategy with developmental benefits. The research is clear: independent play with high-quality open-ended toys builds self-regulation, imagination and concentration. Start early (even 6-month-olds can have 5-minute independent play periods), build duration gradually, and set up the environment so the child can access toys without help. The result is a child who can play alone, and a parent with 20 minutes to function.
Free: The Parent's Guide to Real Play → Independent play wooden toys →Britain's oldest toy maker. Every toy open-ended, wooden, and built for exactly the kind of play the research recommends.