I believe most people who care about privacy don’t trust Gemini or Google in general. So it’s not an issue if you already not using Gemini app. It can be uninstalled (at least for now) even without going alternative ROM way

2.5G with SFP+ port might be tricky. You want to be sure that the SFP+ module you buy does support 2.5G explicitly - don’t assume that any 10G module can negotiate that speed. This might work.