Cool/unusual helpful equipment
Okay, so you're proficient with all weapons from the Close weapon group. This means that if you add the Versatile Design modification to a weapon, you're now proficient with it (and can flurry with it).
You're also already proficient with some pretty useful weapons, such as the Tekko-Kagi which basically gives you Improved Disarm for free.
Good options for Martial flexibility
Dedicated Adversary grants a +2 version of the Favored Enemy class feature, and is normally pretty lackluster unless you know that you're only gonna fight undeads for a whole campaign. It's really useful with Martial Flexibility since you can decide your Dedicated Adversary on the spot.
And there's always the situational feats like Blind-Fight, Deflect Arrows, and Rat Cather to deal with concealment, ranged attacks, and swarms.
Races (besides core) do you like for brawler
Anything is fine, really. But since your Will save has weak progression and you have no ways to boost it, you might want something with a Wisdom bonus. The variant Tiefling heritages have something for every class, so that's often my pick unless I'm forced to play human for the bonus feat.
If you want to take a dexterity race, then I'd recommend you to add the Versatile Design modification to a Scimitar, then Flurry with dex-to-damage from the Dervish Dance feat. Or hold out for an Agile AoMF if you want to go unarmed.
There's some feats that give more options to martial flex. to build on than others. Power attack (not piranha strike), combat expertise, dirty fighting, improved unarmed strike, combat reflexes and weapon focus. Skill focus (stealth) can be used to access owl style etc. if you're short of skill points. You don't need all of these but a couple would be good. I wouldn't have mentioned IUS except that a couple of brawler archetypes do lose it.
Do you have any sort of concept to work with? A class isn't a concept IMO.
A foot soldier conscript sounds like a strength more than dex based character to me. With the possible exception of wild child (bonding with an animal rather than your fellow conscripts sounds possible, especially since you escaped and don't have them around now) none of the archetypes which keep martial flex. look quite right for you.
You know how to use a long spear as a brawler (it's a simple weapon) & that was likely the primary weapon you were drilled in as a conscript. Combat reflexes would be appropriate and like I said above it does lead to a bunch of feats you can flex into - not just ones you'd use with a spear. Panther style (needs wisdom), diabolic style (wants charisma), bodyguard, stand still, vigilant charger and vicious stomp (wants you to get trip or overrun feats).
Both for that and to stay alive with light armor you're going to want some dexterity. Note that you can use a shield and still use the brawler's flurry with whatever weapon (or unarmed strike) you use with the other hand. Since you're proficient with all weapons in the close fighter weapon group a waveblade is an option. It's cheaper to enchant an actual weapon than an unarmed strike. If you'd rather fight unarmed that's certainly an option too; many style feats work with unarmed strikes only.
PF doesn't have anything to represent this but doing a muscle-powered job does tend to build up your strength. If being a medieval/renaissance infantry conscript is part of your backstory I'd feel uneasy about doing the ~ Str 8-10 / Dex 16-18 at the start that dex-to-damage builds tend to. YMMV.
Also getting dex to damage locks you into one weapon. A waveblade is nice, but as a brawler it's also nice to be able to use vicious stomp or panther style for an extra unarmed attack sometimes.