Should be able to incorporate easy starting too. Of course, it will be marketed as a premium feature like in cars 30 years ago before becoming standard.
Might be vital for meeting establishing emission targets.
I'm sure an ECU for a small engine doesn't need that big of a battery anyway and it could be a compact lithium battery the size of a 9 volt battery that gets recharged with each mowing.

Ahh, if only victa had kept producing the thumblatch catcher series, they would be in better shape today!