I think it's a terrible idea, not because of the reasons you have stated for wanting a child (though maybe a little bit) but because you don't seem to have put much thought into the life this child would have.
No doubt he would be loved but I think bringing a child in this world on your own through sperm donation, meaning he won't know anything about his father and therefore half his genetics and half his story when you have already stated he won't have any grandparents or aunts/uncles or any kind of relatives in his life is in my point of view quite selfish.
You would be bringing a child into this world whose entire world and sole source of emotional support and point of reference would be you. Meaning if anything was to happen to you, their entire world would collapse in seconds and they would have absolutely nobody left. You even admitted that if something was to happen to you, your child would end up in foster care. Does that not worry you? That you would be bringing a child into this world who would have no one but you and would be 100% reliant on you and your (hopefully) good health?
I don't know much about my father and his side of the family and it has always been hard for me to have a massive interrogation mark about half my personal story, but because I have had my mum's side of the family it kind of compensated (though never totally). I was absolutely terrified when I found out about death at age 5 and the fact that my loved ones were not immortal and I would have lived in
absolute constant state of anxiety if my mother had been the only member of my family as I would have been crippled with fear of losing her and what it would mean (I was already fearful of it even though logically I knew it would have been very likely my grandma would have looked after me)
And what if they don't like you? Or just don't get along with you? Then they are condemn to having no family left AT ALL from the get go and you are back to square one.
My mother definitely had me to fill a void in her life for example and we don't really get along at all (mostly due to her inability to acknowledge how her actions impact others!) and so I live on another continent 99.9% of the time.
Of course your child probably wouldn't be the only child in the world born under those conditions or similar but I do think going out of your way to bring a child into this world through IVF under those conditions and knowing all of this would be very selfish.
I would focus on making life fulfilling for yourself in other ways and meeting people, the happier you are in your life the more likely you are to meet people and potentially someone to build a family with. And why not foster in the meantime? Or host exchange students so your house feels less empty and you get to share your life with other people who are already keen to be a part of your family for a while ?
Sorry if my post comes across as harsh, it genuinely isn't intended to be. But I do think you would be making a mistake by bringing a child into this world without fully considering what sort of struggle your life could bring for him (long-term) and not just for you (because it's obvious solo parenting is tough!)