Tonga coach Kristian Woolf intends to stay loyal to the players responsible for the rise of the Pacific nation in recent season but confirmed that Folau would be considered for this year's Tests against New Zealand, Fiji and possibly a Williams-inspired Samoa.
The majority of the squad committed to their heritage for the 2017 World Cup and again stuck solid during last year's stand-off with the Tongan National Rugby League.
Despite Folau aligning himself with the TNRL during the end-of-season dispute, Woolf said there were no hard feelings and he had a good relationship with the dual international, who has signed with Catalans.
"Back in 2017 he actually made himself available for a couple of things to speak to the players and have some involvement through the World Cup," Woolf said.
"I can only take him on my dealings and he has been really good to deal with.
"One thing that he definitely displayed during that time is that he is very passionate about his Tongan heritage. He made that really clear."
Folau became the youngest player to represent the Kangaroos when he made his debut at 18 years and 194 days in 2007 and won an NRL premiership with the Storm which was later stripped due to salary cap rorts, while being a member of the Queensland's dominant Origin team from 2008 to 2010.
He was considered among Australia's best rugby union players after switching from a short-lived GWS stint in the AFL in 2013 but was sacked last year for homophobic social media posts before reaching an out-of-court settlement with RA.
While Folau is an exceptional athlete, he hasn't played league for a decade and Tonga has now become a hard side to break into after beating Great Britain and Australia last year.
Broncos rookie Tesi Niu played fullback against Great Britain after an injury to Ata Hingano forced Will Hopoate into the halves and the remainder of the Tonga back line comprised Daniel Tupou, David Fusitua, Michael Jennings, Konrad Hurrell and Tui Lolohea.
Kotoni Staggs replaced Niu in the Test against Australia.
"We have got other guys like Moses Suli trying to break into this side as well so everyone will be considered on their merits," Woolf said.
"While the guys who have done a good job for us in the past keep playing good footy, as they are, there is always going to be a reason to stay loyal to that team that has achieved a hell of a lot over the past couple of years, and particularly at the end of last year.
"Israel is a real professional and in any meetings or dealings I have had with him he has been really good. If he is playing footy that warrants picking him in the side, he will be considered along with everyone else.
"He wouldn't get selected because of who is, he would only be selected because he is the best player."
Tonga are scheduled to meet New Zealand and Fiji in the Oceania Cup and Woolf is also keen to play a Test against Samoa, who are hoping that Sonny Bill Williams will commit to them.
Dates and venues for the Oceania Cup are yet to be confirmed but Tonga's Test against the Kiwis is expected to be in Auckland during the NRL's standalone representative weekend in June, while both nations will play the Bati at the end of the season.
"We are in contact with Samoa on a fairly regular basis and they would love to play us as well," Woolf said.
"That is our traditional rivalry, it is a really big game for both teams whenever we play and obviously at the moment they would like a crack at us to try and knock us off."
Samoa have been drawn to meet England in the opening match of the 2021 World Cup at Newcastle's St James Park and there is keen interest in the possibility of Williams representing his heritage after returning to league with Toronto Wolfpack.
Williams will make his Super League debut against Castleford in a double-header at Emerald Headingly Stadium on Sunday (1.30am Monday AEDT), while Woolf's first match in charge of St Helens will be a grand final rematch with Salford on Friday night.