Your assertion was, "At the very least, proponent of this theory should be able to provide evidence that bats or viral samples from bats were present in the lab

Your assertion was, "At the very least, proponent of this theory should be able to provide evidence that bats or viral samples from bats were present in the lab before the outbreak". Yes, it's clear they were working with live bats of the species that most scientists, even those who believe in the pangolin hypothesis, believe is the natural reservoir of SARS-CoV-2. Multiple papers published from BOTH Wuhan labs describe such bat research. The Wuhan CDC did so much live animal research that they employed collections expert by the name of Tian Jun-Hua, whose work collecting bats is described in a number of pre-pandemic media reports (including several times he quarantined himself after being exposed to gross amounts of bad urine or blood). You can see him doing his work, including live bat collections, in this (government produced) documentary about the Wuhan CDC: https://youtu.be/ovnUyTRMERI https://youtu.be/ovnUyTRMERI But to your question, here's a paper from the Wuhan CDC lab published in a well-known international journal that I happened to have open: Guo WP, Lin XD, Wang W, et al. "Phylogeny and Origins of Hantaviruses Harbored by Bats, Insectivores, and Rodents" PLoS pathogens Before you stop reading and respond, "those are hantaviruses they were studying. Covid-19 is a coronavirus.", let me stop you. My hypothesis, like others who believe this is a possibility, has never been that they were studying SARS-CoV-2 specifically, but rather that the lab, or a lab-adjacent facility, was where the virus accidentally "spilled over" from bats to humans. That said, they were studying bat coronaviruses in both labs. Also, the Wuhan Institute of Virology was doing live bat research. See the many articles about the Institute's "bat lady", Shi Zheng Li, and her research.