Are there any rules for upgrading things like Tinbots and the like for better stats, better equipment and the like either already available or planned?
If nothing is planned I was thinking of letting players do so in the same way theyed upgrade Geists (IE Spend the money or their own XP)
Was also contemplating the same for things like pets / Antipodes but with both of these limiting their max to 3 in skills and focus and max +2 to attributes and with the same limitation on Augments as any PC
there are a couple of approaches you could take. personally, i’d default to the armor customizaton rules on pg. 347 of the core rules, essentially making the players use parts and tech tests to upgrade remotes, with the same challenge levels and complications for similar/dissimilar combinations (e.g. adding a Krab Gauntlet to a Null-Zed Zond? those are parts made for the chassis, so go for it. adding an HMG to your Fanous remote? that’s gonna be tough…). i’d even consider balancing the modifications out with an increased complication range and/or qualities like “Tin-Bot with Issues” from the Nomad career table. and when that 19 or 20 gets rolled, i would strong consider temporarily to permanently disabling the buff/custom equipment–because it’s always the cool thing that breaks when you need it most.
there’s also a good post from inane imp about weapons customization that touches on the same as above but with a more comprehensive layout… i won’t try to duplicate it, you should just check it out.
lastly, i think your instinct to use the geist customization for antipodes and pets is what i would favor too. i think of geists and pets as characters while remotes are generally just equipment. your PCs might gripe about having to constantly fix and upgrade their super cool balance breaking toy, but the drakomon critical to their backstory is probably worth advancing in a more organic/XP progressive manner.
Part of the reason I added “Field Modification” as a another trait to custom weapons was the penalise doing this on the fly with inadequate equipment (same intent as Ad Hoc Modification).
Both are worthwhile to add to field modded REMs (particularly in cases where the modification isn’t a simple 1 for 1 weapon swap), with the potential to use additional Momentum to avoid them (which is why I like Complex Skill Tests for building / modifying things).