Have you considered UDPXY (it’s extremely lightweight and run great in container on RouterOS, I use it on my RB5009 and hAP ac² with only 128MB RAM)? It will introduce a few seconds delay to the streams but other than that, it works well, even for watching IPTV channels on the go over WireGuard. I now exclusively use that for watching IPTV in my local networks instead of multicast because IGMP Snooping on the RB5009 still doesn’t work correctly with VLANs + IPv6. IGMP Proxy is only needed between the upstream interface and the container bridge that has the VETH interface.