start one office from ./dev-dependencies/Collabora or ./dev-dependencies/OnlyOffice by running docker compose up -d in that directory
run oCIS, please see https://github.com/owncloud/ocis. Please note that oCIS needs to use a shared service registry with the WOPi server. You can eg. use "MICRO_REGISTRY": "mdns", (see ./.vscode/launch.json).
run WOPI server in debug mode by using the VSCode run target or by executing go run ./cmd/cs3-wopi-server