> Money may contain a host of infectious agents, including coronaviruses, at any time, regardless of the presence of a novel outbreak. For this reason the WHO recommends — in general — washing one’s hands after handling money.
It became common practice that the delivery personal is leaving the package and backing off. While keeping distance, trying not to engage in further physical exchange.
I'm not aware of any online shops where you can "tip" on top of the payment - e.g. for postal service.
Also, a "tip" is defined (at least for me) as "a thank you for a service well provided". Therefore I can't calculate in advance how satisfied I will be with the delivery, e.g. if it's on time and the person is friendly then the tip will be larger, versus late and cold pizza...