Marian contacted me directly to ask his question. I will post the answer here as well. Question was: "In the template for the sandbox i see there is a link to the CDN, is it possible to use local libs like in UI5-Tooling?" Answer: "the sources are being used as defined in the ui5*.yaml so if you e.g. defined a fiori-tools-proxy middleware the sources will be loaded via the proxy from the defined URL. If you don't use a proxy the libs from ui5*.yaml served from ui5 tooling are being used."
Great session. Sad that Marians question wasn't answered.
Marian contacted me directly to ask his question. I will post the answer here as well. Question was: "In the template for the sandbox i see there is a link to the CDN, is it possible to use local libs like in UI5-Tooling?" Answer: "the sources are being used as defined in the ui5*.yaml so if you e.g. defined a fiori-tools-proxy middleware the sources will be loaded via the proxy from the defined URL. If you don't use a proxy the libs from ui5*.yaml served from ui5 tooling are being used."