To be fair to Wales and Scotland, they've only got limited wiggle room to play with. Scotland and Wales alone couldn't have come close to funding business support and furlough schemes without the UK Government so would've definitely towed the line on the timing of introducing lockdown. Wales still has the 5 mile travel rule which now seems bonkers and Scotland have been piss poor at protecting care homes as has England and Wales, albeit it if not quite so piss poor. I think excess death figures for all three have been higher than most other European countries but, from the non-English perspective, its fair to say England have the worse track record and I guess from the devolved governments' points of view, that's all they need to be able to prove. To be honest its all a bit of a red herring as England will have been hit hardest because of its huge travel hubs surrounding London and also the packed population down there.
I'm absolutely no fan of Boris and co and they have so screwed up in so many ways really (cheltenham races, the Liverpool game, ignoring early lockdown advice from Italy and Spain, f**king up testing and tracing, not testing or quarantining at entry points, not having sufficient protective gear in the NHS, dumping infected elderly patients on care homes, setting a gob smackingly shameful example to the country asking them to swallow the Dominic Cummings bollocks, wasting valuable time 'developing' a now dumped, unusable smartphone app through a crony firm linked to Cummings etc etc) but despite of all that, you can't really say Wales and Scotland have done any better. Northern Ireland have though I guess