Question: Is it wise to connect to the deceased with the advice of ‘spirit guides’?
Answer: Not at all.
[1] This should be practised to have closure: https://purelanders.com/wake (with some amendments to the Guidance text if needed).
[2] This is how to be sure the deceased is alright: https://purelanders.com/sure.
[3] This is how to have more sincere and fruitful mindfulness of Buddha (念佛): https://purelanders.com/start, to better guide the deceased (if still around) and to create more meritorious virtues (功德) for dedication (回向) to them, wherever they are, to have greater well-being.
Buddhists already have the best guide, Āmítuófó (阿弥陀佛), as connected to, with sincere mindfulness of Buddha. With sufficient learning and practice (修学), once in Pure Land (净土) later, as empowered by Āmítuófó (阿弥陀佛), we will be able to find and guide all loved ones, wherever they are.
If pining for communication now, ‘random’ wandering spirits (孤魂野鬼: lonely and ‘wild’ ghosts) might be encountered, who read our minds, impersonate loved ones, ask for favours and offer inadequate advice. Thus, vague ‘spirit(ual) guides’ might be ghosts in disguise, who are unenlightened, still with the three poisons (三毒) of greed, hatred and delusion (贪嗔痴). We should only take refuge in enlightened ones, not unknown beings.