Is the fast of a bedridden person, who is compelled to use the internet due to loneliness, considered complete despite being exposed to internet prohibitions, given his sincere intention to avoid them were it not for his dire necessity?

Whoever intends to do a good deed but does not do it, a full good deed is written for him. However, this does not apply to the man mentioned in the question, as he is not compelled to go online, and he can occupy his time with beneficial matters. And if he needs to go online, there is nothing that compels him to view forbidden things. Sins diminish some of the reward for his fasting, and he should utilize the virtuous days for what benefits him. And perhaps his tribulation is a blessing that pushes him to review himself and repent.