To be honest, I think your position is short-sighted, naïve and lacking in pragmatism.
Right now, in most constituencies, your choice is between Labour/Lib Dem and Tory/Reform. And anyone who thinks Labour getting into government wouldn't be an improvement over the Tories hasn't been paying attention for the last decade. Even if Labour had the exact same political stance as the Tories - which they don't - the fact that they're not nearly as likely to be corrupt, self-serving slime balls makes them an improvement by itself.
Labour needs to appeal to moderate, swing voters. There's no steadfast left-wing voter base in the UK; if Labour can't win over the swing voters they won't get elected - it's that simple. That doesn't mean they're sat there asking themselves how they can be more like the Tories, it just means they need to take positions that have broad appeal and don't just go full-socialism. As much as socialism appeals to me, I'd rather see Labour actually get elected. There's zero chance we go from our current government to a socialist government overnight.
And if I think about where I'd like to see our country in ten or fifteen years, Labour winning this election is the most realistic way for us to get there. Spoiling your ballot, not voting at all, or voting for some candidate who's going to get <3% of the vote isn't going to achieve anything other than a short-lived sense of self-satisfaction. The best thing any of us can do is to pick the least bad of the realistic options. I don't like that that's the system, but it's the system we've got and we either have to work within it or have it imposed on us anyway.
I don't think the Labour Party is perfect by any means. They have some ideas I like, and I'm hopeful they'll unveil more policies I like in the next few weeks. And, of course, there are things I dislike about them. They're certainly not my dream party. But I also think it's important not to let perfect be the enemy of good. We have a chance to improve things, and squandering that chance just because things aren't going to be perfect is fucking stupid.