I'd like the ability to choose what I respawn with.
I should be allowed to choose what extra equipment, and in what quantity, I re-spawn with. e.g - respawn with 2 medkits and 0 grenades, or 1 medkit, 1 rpg, and 1 grenade.
Add the ability to respawn with sandbags.

It can be fancy or simple.


Simple:

A checkbox that says: "Respawn with items held at death"

If checkbox is selected, you respawn normally/legacy- whatever you were carrying at death.
If not selected, you respawn with whatever you last purchased, or if data is unavailable, your items you had the previous life.

If the checkbox is not selected, the game would play out like this:
You spawn with an AK and regular 'nades.
You pickup an m16, and you die.
You didn't buy anything and you unchecked the box for respawn w/ items at death, so the game looks at what you respawned with the last time you died- or in this case, an AK and regular nades.
You respawn w/ AK and regular nades.
You go out and buy an m16.
You pickup impact grenades.
You now have impact+m16.
You die.
You respawn with an M16, and regular nades, since you didn't buy the impact grenades, saving them to you, but last life you respawned with regular nades.

Cannot respawn with things you cannot normally respawn with. (Rares, c4, etc)

Fancy:

A checkbox next to every item slot in armory or in inventory that lets you 'save' that item for respawn. Can be in armory UI, menu UI, or inventory UI, or a combination?

I can tell you that this won't happen.
For now when you die, you respawn with the weapon you had if it's non-rare and if it's listed at your armory. There are also some weapons at the armory which you can respawn with (like the M79) as it would drain too much RP on respawn (the inventory slot is blueish for those items).
The sandbags were respawnable with at some point during early access, but people complained about the RP drain.
For grenades, AT, etc you respawn with half of the max amount you can carry. At some point it was the full amount but again people complained.
Some people also complain about the RP drain on respawn to refill your combat equipment but this is a design choice and can also be seen as a slight "death penalty".

Okay, you told me it wont happen.

Why not? Why can't it happen in some capacity?

Do you like it this way, and damn everything else? (a valid option)

Is this the best way to solve the issue of players wanting to choose their respawning inventory? (because they do)

Is this fun?

Do your players like it?

Is your engine not advanced enough to support these features?

These are tough questions to ask yourself, but I think you should.