Can I run LFM2.5-2.6B-GGUF on an RTX 3090?

Yes

Its BF16 file (5.40 GB) fits in the 21.6 GB an RTX 3090 can use, with room for ≈ 128K tokens of context.

ollama run hf.co/LiquidAI/LFM2.5-2.6B-GGUF:BF16

Files and context on RTX 3090

Each file of LFM2.5-2.6B-GGUF (and of GGUF versions the site has analyzed), and how much context fits next to it, with the context cache in 16-bit or 8-bit.

LFM2.5-2.6B-GGUF on other hardware

Popular models that run on RTX 3090

Assumes 90% of the card's memory is usable and at least 4K tokens of context for one conversation, with the context cache in 16-bit unless noted. Fits leaves at least 20% of that memory for context; Tight leaves less.