> As freestanding environments generally cannot support exceptions, parts of these facilities cannot be included. Specifically, span::at() (since it throws std::out_of_range) and all overloads of std::expected::value() are excluded from the freestanding subset.

Given that the hardnening library mode isn't on by default, only defined what it is supposed to be like, this means as usual security took a second place when designing these features, as there isn't something like std::span::try_at() that would return std::expected or similar for freestanding deployments.