Agree.
I think the fundamental problem here is that a party that wins under FPTP will be unlikely to propose something that may rock the boat that allowed them to win. And while in opposition they cannot implement anything regardless of their desire to.
Crystal ball gazing - one of the key things you need to do when in power is to change and set the agenda. Every government has done this over my lifetime, but often as an opposition coming into an election they are 'timid' as they are playing to the agenda set by the incumbent government.
So I wouldn't be surprised if, when Labour assuringly comes to power, there is a big shift in agenda on constitution/electoral reform. They won't have much money to play with, but these kind of changes cost next to nothing. And therefore it seems completely plausible that a Labour government would use the first term on more minor stuff (Lords reform, bringing back non-FPTP where it has been removed etc) but goes into a 2028/29 election with a manifesto promise on reform of the electoral system for general elections.