As for environmental issues.It looks very efficient to me. Pig being roughly human mass, Im sure Greta thunder**** would approve...I did two such 'interment' ceremonies at sea back in my RNR days. Ashes only.
One with London Division off Spithead, another with Sussex Division off Shoreham.
There used to be a company down in Cornwall that did sea burials - but I think there's an environmental issue that precludes it anywhere within continental shelf waters.
I believe Claygate Naval Cemetery near Haslar is available for ex RN burials onshore.