His predilection for travelling the world in gas-guzzling private jets has led to adverse headlines and accusations of hypocrisy.
But the Duke of Sussex has ploughed on with his sustainable travel campaign, launching a new initiative to rate holidaymakers based on their green credentials.
In a skit broadcast on Māori Television in New Zealand, the duke suggested travellers should be penalised if they use too many hotel towels, drop litter or leave taps running while brushing their teeth.
While many holidaymakers opt for isolated luxury resorts, he urged them to support local communities, contribute to local conservation efforts and create time to "form an authentic connection to nature, people and culture".
In a pre-recorded video promoting his Travalyst project, he said: "The Māori culture inherently understands sustainable practices and how to take better care of our life-giving land, which are critical lessons we can all learn – and that is why I'm here with you on Te Ao with Moana to share a new kaupapa [initiative].
"For our first campaign, we're encouraging people to flip the script. We're always being asked for our feedback on our trips and experiences, and what would happen if our holiday rated us. It's an important question to ask, and we want all of you to help us answer it."
A poll published on the Travalyst website gives users a rating based on how they answer five questions about their holidays. It then offers tips on how to make better choices.
In the skit filmed in California, which doubled as New Zealand woodland, the duke is shown jogging in a "Girl Dad" T-shirt and Apple Airpods and speaking in Māori.
He is chased by a team of "rating agents", played by New Zealand actors Rhys Darby, Dave Fane and Rena Owen, who accuse him of dropping a sweet wrapper at Auckland's Bethells Beach during a royal tour in October 2018.
Darby explains that they are trialling a system in which holiday destinations rate their visitors, giving the duke three stars out of five. He gives him positive feedback for only using one towel instead of the 12 provided, buying local honey and turning off the tap when he brushed his teeth.
As Fane catches up with them, the two agents argue about whether they are rating "Harry Stylee" or the "Stylish Harry". Owen then arrives in a van, greeting the duke, with "long time, no see" as he says hello in Māori. She apologises for her colleagues' behaviour and says they are still in training.
In a separate segment for the programme, the duke told viewers he had always felt a deep connection and respect towards the Māori people.
"Most recently, when I visited with my wife, we were touched by the connections we built and the incredible memories we have from our time there," he said.
"We were particularly honoured to meet with young people who were dedicated to the Māori culture and dedicated to giving back to their communities and their culture."
He described New Zealand as a country of "sustainability pioneers" and said he was particularly impressed by the recent efforts of the "tiaki promise" to care for people, place and culture.
"Every year, more and more of us want better options," he added. "And for the first time, travellers are striving to make that a reality for everybody who wants to support local communities, travelling with kaitiaki values and looking after nature and wildlife."
Moana Maniapoto, who hosts Te Ao with Moana, told viewers she was so surprised to be offered a "no strings attached" interview with the duke that she initially thought it was a scam.
After "a lot of to-ing and fro-ing", she said the interview did not happen but added: "It's interesting to hear someone who's a royal speak about Māori values, given our history.
"We are open to talking to anyone … anything that particularly resonates with our values as Māori - whether we agree or not. I'm hoping that we will have an interview further down the track to tease out that relationship between Māori and the Crown."
In February, the Māori party of New Zealand called for a "divorce" from the Crown and removal of the Queen as New Zealand's head of state.
The duke founded Travalyst, a nonprofit dedicated to making sustainable tourism mainstream, in 2019.