But the F35 is a replacement for the A-10 as well as the F-14, F-15, F-16, F-18, U2, B1B, B2 and the B52.@oldsoak mentioned that guns hadn't been used recently, which is true.
Tornados had guns but were used up at medium-level. Strafing wasn't happening from there.
Yes, the Typhoon has a gun - the same 27mm Mauser as the Tornado. But, again, it's used up at medium-level out of the way of small arms, AAA and MANPADs. We've not been doing any air-to-air stuff.
The F-35B faces the issue of weight, which has led to a lot of effort to remove it where possible. Nevertheless, it's still 3,500lb (or thereabouts) heavier than the -A and has a maximum take-off weight that is 10,000lb lower. Hence also the different g limits (9g on the -A, 7g on the -B, 7.5g on the -C) - some structural bits have been thinned out to get the weight down.
And hence also the pod. But, when and where would you use it? You don't want to be down on the deck making strafing runs in your uber-expensive stealth aircraft. You're likely also going to wanting to be doing air-to-air at arm's length - like AMRAAM or Meteor arm's-length.
The gun pod exists but I doubt anyone's going to be looking to put themselves in a position of having/needing to use one.
Haven't you heard? It's a much better platform for Close Air Support than the aging and vulnerable A-10.