FWIW, amongst the current recurring cast, we have the following alignments of which I am aware:
Marten - Mostly hetro but with some gay leanings;
Claire - Mostly hetro but a little ambiguous (she once said something that has a reasonable interpretation of her finding Dora attractive);
Faye - Hetro;
Pintsize - Pansexual (I'm expecting some flak about this but he seems equally attracted to both human and robot and to both expressed genders; however, this is Pintsize; it's difficult to know what is real and what is an elaborate prank);
Dora - Bi and seems to be pretty much balanced on the mid-point of the scale;
Hannelore - Hetroromantic but, by effect of her mental health issues, probably asexual in any meaningful practical terms;
Tai - Lesbian but she loves to tease;
Steve - Very, very hetro;
Bubbles - Definitely seems to be anthrosexual (attracted to humans) lesbian;
Momo - Anthrosexual hetro;
May - Mostly asexual beyond a basically aromantic interest in certain aspects of human reproductive and waste evacuation anatomy;
Brun - Definitely seems hetro;
Renee - Hetro;
Elliott - Just revealed to be somewhere in the bi spectrum;
Jim - Hetro;
Veronica - Hetro (irrespective of what she may have done over the years in a professional capacity).
So, of these sixteen characters, nine are hetrosexual or as close to it as really makes no odds. We only have two homosexuals (Tai and evidently Bubbles) and everyone else is some flavour of bisexual with the exception of Pintsize (who is difficult to read accurately because of his sense of humour)* and May (who has shown only prurient interest in others sexuality and has shown no real interest in being involved herself).
* - Note on Pintsize; his only actual known sexual encounters have been with fellow synthetics. It's possible that he is mildly-bi with no anthrosexual leanings beyond a near-demonic joy in yanking his human friends' chains.
First of all I wanted to point out that many straight women evaluate the attractiveness of other women all the time. Given the vicious pecking order that so often exists among women WRT physical attractiveness, it is kind of unavoidable. In Claire's case, since Dora is Marten's ex, her attractiveness is something that could be a potential source of anxiety or self-doubt from time to time.
In the case of Bubbles, it is entirely possible that she could have a crush on Faye specifically. Consider the possibility that the differences between AI and human are greater than the differences between male and female. Especially for a less socialized, less human-identified AI like Bubbles, the issue may be less "how can I be in love with a man/woman?" and more "how can I be in love with a biologic?"
Momo, on the other hand, is highly socialized and human identified--that almost seems to be her primary function, to the extent that AIs have programming, and her awkward blushing reaction to bishonen cuties is part of her "proper young lady" persona. She was caught making out with a Magical Love Gentleman doll that Marigold won at an anime convention, so I think her attraction is not limited to humans per se, though it is very specifically targeted in terms of appearance.
I don't think Brun relates to humans well enough for the usual metrics to apply. She seems to be ignorant of all the basic human conventions. I am reminded of the character Dina in Dumbing of Age whose initial reaction to couples having sex was "Mammals are weird." She later decided to become Becky's girlfriend despite no prior indication of attraction in that direction, and I cannot help but wonder if it is
literally an experiment, an attempt to find out why this "sex" thing is such a big deal.