Standard Skill
Siris gains a blessing that gives CC-resistance and 25% reduced damage taken, which lasts for 10s.
If Siris dodges during the blessing, she gains extra Kinetic damage to her next shot.
With its first Neuronuc buff, the shot also gains +50% Dmg dealt to shields, which is a large bonus against shields.
With its second Neuronic buff, dodging also reloads 1 shot.
This has a 15s cooldown, but it only goes on cooldown when the 10s blessing ends, so it lasts 10s every 25s.
The extra damage from this skill isn't particularly high, and the requirement to dodge every single shot means it really isn't much of a dps increase at all.
The tediousness and time needed to dodge before each shot means that Siris' Standard Skill is basically just there to improve her survivability, not her damage.
The extra damage after a dodge means Siris doesn't really lose dps from dodging, but she doesn't gain any dps beyond just shooting normally.
Note that the damage-per-shot from this skill maxes out at about the same amount that Fritia - Little Sunshine's support buff does (11% ATK for both), except that Fritia's support skill applies her buff to every shot during its duration, rather than just the next shot.
Ultimate Skill
Siris creates a dome that provides dmg absorption, increased movement speed, CC-resistance, as well as repelling enemies for 10s.
With its first Neuronic buff, when the dome ends it restores HP equal to 20% of its remaining shield.
This is a very small heal, to the point of being a functionally negligible increase to Siris' survivability.
Siris' ultimate skill doesn't do any damage, and is basically useless for healing you, so there's basically no reason to ever use it - if you actually need an operative that can heal themself, there are other operatives that do that vastly better, for example Clarina - Crimson Moon or Eatchel - The Cub, both of whom also deal Kinetic-damage, and out-dps Siris by a vast margin.
If you only need some survivability, you should take a dedicated healer, such as Yao - Quiet Quitter.
Support Skill
Siris deploys a cover in front of her to block enemy fire.
This cover is neither a Shield nor an Auxiliary Unit.
The cover has very high HP, and can take a lot of damage.
Since it doesn't actually boost your operatives damage at all, Siris' support skill is not very good.
If you do actually want more survivability, you're better off taking an actual healer like Yao - Quiet Quitter or Chenxing - The Observer rather than Siris.