McGrath suffered a dislocated shoulder against Celtic earlier this month while former Aston Villa youngster Doyle-Hayes injured his foot against Aberdeen.
Goodwin feared both Irishmen – who are among his top performers – could be out for the remainder of the season but the good news for the Buddies boss is the pair are both likely to be available before the split as Saints look to clinch their place in the top six.
Their absence has allowed Flynn to reclaim his spot after six months out with a serious knee injury.
But the midfielder wants to see Saints back to full strength as soon as possible as he insisted he is ready to fight for his jersey.
"Suspensions and injuries have helped me get back in the team but the bigger the squad you have the better," he said. "I definitely don't want to see boys getting injured and hopefully the likes of Jamie and Jake can come back soon.
"What's really important though is having players ready to step up when called upon and I think that's what has happened this season. I think that's what has happened with me. I'm always ready and look to play my part whenever I can.
"We've had loads of different challenges this season like Covid but I think we've handled it really well. This latest bout of injuries is no different but hopefully we can get a few more boys back before the split."
Saints – who have drawn their last three matches – play their game in hand on Wednesday night as they host Motherwell.
Victory will help solidify their place in the top half of the table and open up a four-point lead over nearest rivals Dundee United.
The Buddies then have clashes against struggling duo Ross County and Hamilton either side of a trip to Rangers but Flynn said: "We can't look further than the game on Wednesday.
"It's that old cliche about the next game being the most important but it is as it's a real chance for us to get three points and cement our place in the top six.
"We thought we'd have got more from our last two home games so hopefully we can make amends on Wednesday and open up a bit of a gap."