Coincidentally, we did look at integrating the “screamer” fork of QEMU into EaaS for Rhizome just last week in Integrate "screamer" build of qemu-system-ppc (#20) · Issues · Emulation-as-a-Service / eaas · GitLab.
It is pretty hackish currently and I am not familiar with the EaaSI interface at all but you might be able to import it (image name “registry.gitlab.com/emulation-as-a-service/emulators/qemu-eaas”, tag “screamer”). In EaaS (not sure about EaaSI), you then have to enable “WebRTC Audio (Beta)” and “XPRA Video (Experimental)” (or it will probably not work at all). Additionally, you have to specify -audiodev pa,id=pa,server=/emucon/data/sockets/pulse-iosocket as “nativeConfig” (“Emulator configuration” in EaaS’s UI).
If you want a relative mouse pointer, adding -device usb-tablet to nativeConfig might also help (but might also make things worse).