That looks to have the potential to go wrong quickly.......  There is nothing that can't be fixed with a hammer😜😜
FFRR 4.4 SDV8 Autobiography Santorini Black.
Fiat 500x 1.4 multiair Lounge 2015
2010 LR D4 Commercial 2.7 TDV6

URLs could do with being a bit more visible... .
Experience is the only genuine knowledge, but as time passes, I have forgotten more than I can remember
Volvo V70 P2 2006 2.4 Petrol 170bhp Estate SE
MG Midget Mk1 1962

Previous: L322 Range Rover TDV8 3.6 2008; L322 Range Rover TD6 3.0 2002; P38A Range Rover V8 1999

Engine needs to be as near as possible to full running temperature when removing glow plugs

Yes, there is an argument for and against this:

Cold; the metals and threads are "decompressed" and therefore not under tension, supposedly making it easier to undo

Hot; the metals and threads are compressed, under tension but the heat can produce less friction, supposedly making it easier to undo

Given the relatively light touch I applied to the plugs, I don't think it would have made much difference? I did put the hot air gun one of the plugs for a few minutes, the hex still span

It is all past that point now, FFRR starts up after a few turns of the starter motor, so all is not lost, apart form having four brand new glow plugs in stock!

I would have a go at extracting them, using something like a reverse thread extractor drill/bit, but would worry about the inner core dropping into the cylinder when I break the top of the plug off .... .
Experience is the only genuine knowledge, but as time passes, I have forgotten more than I can remember
Volvo V70 P2 2006 2.4 Petrol 170bhp Estate SE
MG Midget Mk1 1962

Previous: L322 Range Rover TDV8 3.6 2008; L322 Range Rover TD6 3.0 2002; P38A Range Rover V8 1999