But again, how do AIs in general get chassis? Bubbles' chassis seems to have been a 'gift'/result of military service, Roko we don't know. But a new AI comes out of the creche, may want a mobile chassis, may not. How are they paid for? Are there parents who pay as human parents effectivelypay for their offspring's chassis? Is there a kind of bond servitude like McCaffreys "Ship who... series"?
Roko did say she'd had her original chassis
"since I was born". So having a body straight out of the creche is definitely a possibility.
With humans, of course, the parents are responsible for taking care of the child's needs and providing appropriate clothing, housing, and so on. It seems pretty reasonable to me that whoever commissions an AI mind to be created is also responsible for deciding whether the AI is to be initially embodied or not, and providing a body if so. This would certainly have been the case earlier in the history of AIs when they were still legally property.
I imagine that at first, AIs were commissioned for specific tasks, and provided with bodies as required by the nature of the tasks - the military gave theirs bodies like Bubbles' (or Pintsize's old one), the AnthroPC makers went for "cute and not too expensive", and... well, I don't know what the spiderbots would have been for. Once AI rights became established, the whole situation undoubtedly got murkier - I should think the right to embody, disembody, or change bodies was one of the fundamental parts of that package, as well as more obvious rights like being able to resign from a job.
But then what's the incentive to make new AIs if you can't guarantee that they'll choose to work for you? I expect this would be handled somewhat similarly to how we handle it for humans, on a contractual basis. One way to set it up would be for various consortia to fund seed pools of AIs with varying embodiment options. While in creche the AIs could experiment to see what kind of embodiment, if any, felt natural to them. On maturity the AIs would be able to choose their final embodiment option and seek employment in areas they find suitable; we'd hope that the spread of what they want to do roughly matches the spread of available opportunities, and correct any mismatches by offering more money or other advantages for roles that aren't attracting enough interest. If they chose to hire out to a member of the underwriting body, for a set minimum period, they would get their chassis for free; if not, it'd be a debt they have to eventually repay (probably with low interest and generous terms - so a bit like The Ship Who Sang but without the "most of them are in debt their whole lives and can never leave their job" aspect). If they chose a disembodied existence and independent work there might still be a nominal debt for their creation, but it seems that a good humanoid chassis is much more expensive than that (otherwise Marigold and Marten wouldn't have been able to afford AnthroPCs in the first place).