Admittingly, the only experience I’ve had with Mando players thus far are myself when I was a wee lad to the system, and with one of my players preparing their next character for the sequel campaign, and both of them will have been or will be the sole Mandalorian of the group.
Looking at the base Mando armor, or as I did at first glance of the system, Heavy Battle Armor, 4 to 5 HP is a rather good amount to start with as a base and gives alot of flexibility. Now I see your main concern is that you can’t load up on weapons, else you have no room for utility (or other weapons) and that too was my concern with my character, until I stumbled upon a little beauty called the Model 2 Wrist Mount (found in Dangerous Covenants.) My main concern with giving a character the ability to have another 3 weapons at the cost of 1 HP is that, well, that’s a low risk-high reward venture for them and they’ll become a walking-talking-shooting armory. My math is like this: 5-2=3+6=9, only at the cost of 1,000 credits, and 2 encumbrance.
Now what the wrist mount does is it takes 2 HP on a Ranged light weapon, and then attach hands free to your wrist (or forearm, or where ever, GM willing). For certain weapons, like the Flamecaller (the only ranged light flame thrower, which doesn’t have bad stats for what it is) the encumbrance is gonna be a tad wonky sitting at a good 4, but if the GM is willing to get past encumbrance values, then that was your biggest concern next to certain weapons needing a use of Tinker to reach that 2 HP requirement, which is fine if the Mando is already trying to trick out their armor since you can only use Tinker once per item, so their armor wont be loosing out after its one Tinker use anyway!
I also wanna touch on two examples used: Sabine was often shown to be a great mechanic, and didn’t have contact with other Mandalorian’s for years, so likely modded her armor on her own very often. Din, on the other hand goes to have someone else do it, and before he gets his beskar outfit actually meets the HP requirements if we consider each thing he has 1 HP (2 flamethrowers, 1 whipcord, 1 tracking system) Its only after he has his armor upgraded (by someone else mind you, which could likely make it a special item in game terms). I don’t think Din is mechanically inept, but I don’t think he knows much more than how to repair a couple ship components, much less modify beskar armor.
One last thing I want to bring up in opposition: crafting rules: I’m not totally savvy on it in its entirety, but one golden thing I noticed in it is the armor crafting, in specific the augmentative armor. Without extra results, it grants the wearer an available 6 HPs as a base! That doesn’t include Tinker, or one being able to add, I think a max of, 2 more HP through getting Advantage and Triumph on rolls to craft it. So it is ACTUALLY possible to get 9 HP in the game without homebrew in the first place. It is very min-maxed when explained, but I think could be great for a narrative if your Mando player essentially learned how to straight up forge armor themselves instead of just modding it, or you could always have another forger make them that, and then slap the Mythosaur skull somewhere on it.
But all that said, I agree with your recommendation on it: if your entire group is Mando then let it rip, if it’s one (or Force forbid 2), you should probably pass for balance reasons. And in my experience, if it’s a very light weapon, IE the dart launcher (and not the explosive type, mind you) I won’t even bother with the HP in certain cases. In favor of homebrew, I’ve also been working on a Mandalorian Survivor universal tree, which I think I want to get around to showing off at some point soon, but it in essence deals with the need for Cortosis Weave as an attachment to saber-proof ones armor.
But yea, those are my 3 in the morning thoughts. I’ll probably look back in the morning and ask myself “why did I say that.”