Requirements for such a build:
Advanced Melee Weapon Proficiency/Specialization
Quick Draw (to be able to combine drawing with a full attack)
Returning and/or Called Weapon Infusions
Bonus points for:
Triple attack on full attack
Heavy Armor (since you'll want Strength to hit instead of needing to max Dex)
Benefits for having high strength (melee bonuses / resolve points / strength skills).
Your best bet is a Soldier. Runner up is a Solarian.
A Kasatha Hit and Run Soldier with maxed strength, a two handed Reach weapon, Quick Draw, and throwing weapons could be interesting. I think the 3rd level gear boost melee striker damage bonuses would apply, as most thrown weapons are melee.
Alternatively, go bombard and quick draw your free grenade each fight, then switch to more traditional thrown weapons.
A Human Solar Weapon Solarian with Heavy Armor and Quick Draw would also be an interesting choice, adding Photon mode damage to the thrown damage. Solar Weapon in one hand with thrown weapons drawn as needed in the other.
Those are what come to my mind at least.
How viable would it be for combact do you think? I did a brief analysis and found that it should actually be ahead of many of the single target ranged weapons at the highest levels, and a lowest levels, but be behind in the mid levels. What are your thoughts?
Mostly this seemed to be because of the gap between levels of starknife. you have to wait until level 8 to get a better than level 1 starknife, and if you are using more than one you'll have to wait even longer as you can't afford multiples of on level items.
Given you can't really afford to have all equipment at maximum level every level, most characters are going to be only be buying new weapons every few levels, so the mid-level relative dips in damage won't matter much, as the long arms characters will also have reduced damage at some levels where they didn't buy the latest and greatest gun.
If you buy the highest level starknife when it becomes available, you'll be doing fine damage. They're available at 1st, 8th, 12th, 16th, and 19th. Damage from weapons doesn't increase much in the 1-6 levels, and its at those levels the bonus from strength will be a much bigger factor.
Comparing a max strength throwing character to a max dexterity long arms character, the throwing character will be significantly ahead at low levels, and about even at the mid and high levels. should always be ahead in damage.
Starknife Thrown vs Kinetic Longarm
1st level: 1d4+4 (6.5) or 1d6+4 (7.5) vs 1d8 (4.5)
5th: 1d4+10 (12.5) or 1d6+10 (13.5) vs 1d10+5 (10.5) or 2d6+5 (12)
10th: 4d4+17 (27) vs 3d8+10 (23.5)
15th: 4d8+23 (41) vs 5d12+15 (47.5)
(however at 16th, you can get 8d8+24 (60) vs 6d8+16 (43)
20th: 8d12+29 (81) vs 12d8 (54)
So damage averaged over all levels will be higher and you can switch between ranged and melee seamlessly. The disadvantages are lower range and needing the called (only out to 100 feet) or returning property on the weapons. You'll also need multiples if you want to full attack. Also, likely lower dexterity reducing AC somewhat unless you're using heavy armor.
Looks completely viable to me. You are basically doing melee damage (the best damage in the game) at short range, at the cost of an extra weapon or two.
A starknife with the called or returning fusion is definitely the way to go. It's pretty viable right out the gate: a tactical starknife with the called fusion is 230 cr, well within the budget of a starting character. You actually save some money (overall) because the starknife essentially takes the place of both a pistol and a melee weapon. Also, with Str adding to the attack bonus of thrown weapons (as well as damage) in Starfinder, it's a good option for a melee-focused character.
The only real problem is the wide gaps between the item levels of the various types of starknives (especially the tactical starknife and the sintered starknife). The ones you want are usually a bit of a stretch to obtain at the level you want them at (compared to other weapons).
Its fairly expensive to maintain. By the mid to late game you'll need 3 weapons at least 3 hands. But if those are things you can overcome than you're damage output is actually pretty good.
Quick draw allows to draw the weapon as part of a full attack, so you don't necessarily need 3 arms for the first full attack.
Depending on GM they might allow you to catch a returning starknife with a hand that is already holding a starknife, since you could clearly hold them in one hand, but not necessarily wield them. Given it's magically flying back to your hand under it's own power and takes less effort than shifting weapons between your hands, this is perhaps not unreasonable. Quick draw would then let you draw it from being stored on the carrying hand to your free second hand.