Healy, his country's record scorer with 36 goals, is currently unattached having been released by Bury in May.
The 34-year-old is among three players without a club that O'Neill has opted to leave out of his party for the rearranged Group F game at Windsor Park next Wednesday, along with defender Chris Baird, let go by Fulham this summer, and midfielder Paddy McCourt, whose last employers were Celtic.
The manager says the trio are on standby, though, and regarding Healy, he told Press Association Sport: "David still has loads to offer I believe.
"I think if he finds a manager who has faith in him and gives him the opportunity, he is more than capable of scoring goals for a club and still at international level.
"I think it is very difficult for any of our players who are unattached at the minute, and having spoken to the players themselves, they are in full agreement with that."
O'Neill has also chosen not to select New York Red Bulls' Jonny Steele, who he last month suggested would "get his chance soon".
Asked about the midfielder, O'Neill explained: "With this being a friendly international day, we can call players in but we can't prevent them from playing for their clubs.
"Jonny has a game this weekend so he probably would have got to us late on Monday or possibly even Tuesday. It would be unrealistic to ask him to do that.
"I did discuss the situation with (Red Bulls sporting director) Andy Roxburgh and I think we both felt it may be better for Jonny if we looked further down the line a little bit."
The Russia game is happening next Wednesday after heavy snow and icy playing conditions in Belfast saw the original fixture postponed in March.
West Brom midfielder Chris Brunt is another absentee from the squad as he has to serve a one-match ban after picking up a yellow card late in the last qualifier, a 2-0 home defeat to Israel which did take place in March.
Kilmarnock's Sammy Clingan misses out as he is nursing a knee problem, while O'Neill will monitor the fitness of a further midfielder, Rangers' Dean Shiels, who has made the standby list along with his club-mate, striker Andrew Little.
In terms of incoming personnel, O'Neill has called on three forwards unavailable to him for the Israel game in new Palermo signing Kyle Lafferty (back from suspension), Brentford summer recruit Will Grigg and Derby's Jamie Ward (who were injured).
Martin Paterson - now a Huddersfield player - and Inverness' Billy McKay are the other strikers involved.
O'Neill, whose men have scored only three goals so far in a qualifying campaign that has seen them draw three and lose two of their five contests, said: "We have created chances, there is no doubt about that - in all three of our home games we have created a lot and we haven't capitalised on that, which is probably the biggest disappointment.
"The opportunity is there for someone like Kyle, Martin or Jamie.
"Kyle is at a new club in a new country and I think it is something he is looking forward to. Hopefully we see that in his international form."
With their three points, Northern Ireland are currently fifth of the six teams in Group F, a point behind fourth-placed Azerbaijan, who have played two more matches.
Russia are second on 12 points from five games, sandwiched between leaders Portugal (14 points from seven games) and third-placed Israel (11 points from six games).
O'Neill is still searching for his first victory since being appointed as Northern Ireland boss in December 2011, having overseen a total of nine fixtures.
And he thinks his team - who drew 1-1 in Portugal in October - can thrive as the underdogs next Wednesday.
"We are playing one of the top sides in Europe and, I believe, the strongest team in the group," O'Neill said.
"That tends to be when Northern Ireland are at their best, and the players have everything to gain.
"So we can look forward to this game and really make sure we try to get a big scalp for the people of Northern Ireland. We have done that in the past."
Meanwhile, the Irish Football Association has today announced a four-year extension with Vauxhall Motors that will see the British vehicle manufacturer maintain its position as lead sponsor of the Northern Ireland national teams.
The deal, which began in January 2011, will now run until July 2018, up to and including the World Cup finals that year in Russia.