I would be interested what you do think about using melee weapons on Survival mode. I play on Survival and it's ok with guns but I don't get it with melee. The damage is so low. For example in one Med lab currently I faced three normal ghouls and a glowing legendary one and I didn't succeed to kill and survive with my melee weapon (Kremvh's Tooth). It's relatively easy with my combat rifle.

I have only 6 points in strength and a +1 strength combat armor, at Lvl 28 I have 3 points in the melee perk. Are 10 Points mandatory? With a superhammer it is much worse than with a medium weapon, you cannot prevent the foe from hitting you because it is so slow and the damage is very low for a heavy piece of steel with a rocket on it. With damage factor 1 it is not a problem but with 0,5 I'm too slow with killing. Taking chems helps but that's not what I would like to do. Using power armor all the time is not an option.

How do you (if someone did) kill a Deathclaw, Radskorpion, a bunch of legendary flying insects, the Mirelurk Queen or, even worse, The Sarge with melee?

I tried it, didn't like it. Simply because it too often means putting yourself in harms way and dying. I think melee only works (or works best) with a combination of guns and stealth. Stealth, melee, ninja + blitz is supposedly very good, but I never got that far before I abandoned the character.

In truth, my MO is to pair melee with at least one ranged thing, like heavy weapons or pistols. Explosives help, too.

I use a lot of melee but I'm not exclusively melee. I rely on stealth to ensure that I get the jump on the enemy, assess from afar, and plan a strategy. Often times I'll pick off one or two enemies from afar with a sniper, plant a trap or two, and lure any remaining to where I can get in close with the melee. I'm also finding that VATS and melee work significantly better in FO4 than in previous games. I've been able to use VATS pretty heavily with an Sharp Aluminum Baseball bat to take out some enemies. As far as taking on a deathclaw, I can't see that happening. I essentially never use power armor and deathclaws have the ability to instakill you outside of power armor. No chance on that happening any time soon. I'm also only level 14 or so at the moment. If it changes later I'll certainly let you know.

Always have at least one range weapon with your melee. .44 Pistol is a great range weapon to go with melee.

Also, don't underestimate weapon bashing. The kill move with weapon bashing is a bit OP and triggers too easily. (Even on Survival, I can run around a raider camp and kill most of them in one hit just because of the weapon bashing kill move).

For melee to do good you need heavy agility/luck investments and heavy vats play.

Not true. I play a straight up Strength, Endurance and Intelligence. Sometimes power armour and sometimes combat armour. You just need a chem focused build, and get some defensive perks aswell. Get a sledge and start smacking, its quite powerful. Yes the assassin playstyle focused arounds vats and sneaking works aswell, but i find them equally powerful and satisfying.

You can use power armor all the time, at least after a certain point like level 3 nuclear physicist, barter 2, high enough enemies to drop worthy loot and a water bottling plant. I started using PA regularly when i had 70 cores now i have 112 cores. PA all day long. but I also trade all my extra guns for cores. Run through buildings quicker and carry more loot in one trip. Then instead of going back for scraps just go somewhere new. It'll most all respawn again anyway. I havnt really tried melee yet, just started feeling comfortable bashing radroaches with the rifle stock.

Survival is doable with any build, as long as you wear power armor and keep it fully upgraded every time you can.

Blitz and Critz are insane, like doubles-quadruples your damage and can't be block/stagger locked. NonVats is surely doable, but if the OP opts for VATS even Survival becomes a joke and is likely the "easy" route due to how block/stagger works and how OP blitz is. And nonVats against legendary deathclaws, assulatron dominators, suicide bombers, and mirelurk queens on Survival sounds like a pain tbh.